（）不是焊接钛合金时容易出现的问题。A．裂纹 B．容易沾污，引起脆化 C．气孔 D．

为了测定牛奶的密度，将一袋牛奶倒入烧杯中，测出牛奶和烧杯的总质量为320g，然后将其中部分牛奶倒入量筒，量筒示数如图所示.再测出剩余牛奶和烧杯的总质量为254g，则量筒中牛奶的质量为 _______ g，体积为 ________mL，牛奶的密度为 _______ g/cm³。

It took nearly eight years for the new heart drug BiDil to win approval from the Food and Drug Administration—and it won that approval only after its maker, a small company called NitroMed, repositioned it as a treatment earmarked for African Americans. But if NitroMed thought getting BiDil past the FDA was hard, wait until it tries marketing the drug to its target group. Even during its clinical trials, BiDil ran into resistance. Says Dr. Theodore Addai of Nashville’s Meharry Medical College, who had to enlist black patients for a 2001 trial: "We had to try to persuade them that this was not another Tuskegee. "
He’s referring to the infamous Tuskegee experiment, conducted by the U. S. government from the 1930s to the early ’70s, during which doctors denied nearly 400 black men in Alabama treatment for syphilis in order to observe the disease’s long-term effects. The scars left by Tuskegee are slow to heal in the African-American community, and many blacks remain deeply suspicious of anything that approaches the emotionally charged intersection of race and medicine.
The AIDS epidemic is a prime example. According to the Centers for Disease Control, blacks account for 50% of new HIV and AIDS cases in the U. S., although they represent only 13% of the population. African-American women are especially at risk; their annual AIDS case rate is 25 times that of white women. Citing those statistics, significant numbers of black Americans subscribe to various AIDS conspiracy theories. According to a poll conducted for the Rand Corp. last January, 53% of black Americans surveyed believe there is a cure for AIDS that is being withheld from the poor, and 15% believe the disease was created by the government in order to control the black population. Phil Wilson, director of the Black AIDS Institute, says such attitudes are hampering his work with antiretroviral drugs, "The most common thing we hear with AIDS drugs is, ’Oh, they’re going to experiment on you,’" he says. "The most cited example is the Tuskegee trials, even though most of us don’t even know what Tuskegee was."
Tuskegee aside, the discrepancies in medical care between blacks and whites in the U. S. are real and persistent and not explained by differences in economic status alone. In March 2002 a study by the Institute of Medicine at the National Academy Of Sciences found that even after controlling for such factors as income and insurance coverage, minorities in the U. S. routinely received lower-quality health care than whites. Matters were not improved in the early ’90s when some Governors and state officials tried to mandate the use of a newly approved five-year birth control device called Norplant as a way of curbing teenage pregnancy and reducing welfare costs, a campaign that instantly acquired racial overtones.
In that context, it’s not surprising that the idea behind BiDil—the first drug approved for a specific race—has been controversial from the start. The drug is actually a combination of two older, generic medicines. When it was first tested on the general population as a treatment for congestive heart failure—a gradual weakening of the heart-the FDA ruled that the results were not statistically significant. It was only when the drug was retested on patients who identified themselves as African Americans that tangible benefits emerged: a 43% reduction in the death rate and a 39% reduction in hospitalizations.
Critics point out that while the trials showed that BiDil saved lives, they failed to show whether the drug worked better in blacks than in other groups or that it worked only in blacks. "Race is a placeholder for something else," says Dr. Clyde Yancy, a cardiologist at the University of Texas Southwestern Medical Center and a BiDil investigator. "And that’s probably a mix of biomarkers, demographics and genes."
NitroMed declined to comment on its marketing strategy, but some doctors voiced concern that the company remains sensitive to African-American fears. "I hope they market BiDil with great caution and care," says Gary Puckrein, executive director of the National Minority Health Month foundation. "This really isn’t a race drug but a drug that works in specific populations for reasons we don’t yet understand.\

What is Tuskegee Why did the doctors have to tell black patients "that this was not another Tuskegee" when they were trying BiDil on them(para. 1)

ABS轮速传感器的功用是检测（），并将速度信号输入ECU。

A.行驶的转速

B.制动的转速

C.车辆的转速

D.车轮的速度

明敷接地扁钢或圆钢应涂成（）色。

A、绿

B、蓝

C、黑

什么事健康的生活方式？