从法律意义上讲，工程招标和工程投标的行为分别是( )。 A．要约、要约邀请

650÷50=13

13+45=58

58+60=118

综合式：______．

如图所示，竖直墙面与水平面均光滑绝缘，A、B两小球带有同种电荷，B球被限制在墙面上的一竖直的条形凹槽内（槽是光滑的，小球只能在槽中沿竖直方向运动，图中槽未画出）．用一指向凹槽的水平力F作用在A球上，两球均处于静止状态，现将A球向凹槽方向缓慢拉动一小段距离后，A、B两小球可以重新平衡．则后一种平衡状态和前一种平衡状态相比较，下列说法正确的是（　　）

A．A、B两小球间的库仑力变大

B．A、B两小球间的库仑力变小

C．A球对地面的压力变大

D．A球对地面的压力不变

汽轮机因（）造成带不上满负荷？

A.继动器滑阀活塞卡涩

B.速度变动率大

C.蒸汽参数低

D.喷嘴损坏

The United States counts its population every ten years, and each census reveals that the racial and ethnic mix is changing dramatically, so by the year 2050, the "average" American will not be descended from (1) , but the majority of U. S. residents will trace (2) ancestry to Africa, Asia, the Hispanic world, the Pacific Islands, or the Middle East. Once the United States was a microcosm of European nationalities, (3) the United States is a microcosm of the world. The United States is (4) considered a "melting pot" society by many of its residents. (5) , many people prefer the term "salad bowl." They use this (6) to describe American society. American society will soon be (7) nonwhite. "Melting pot" implies that the different ethnic groups blend together (8) one homogeneous (9) , "salad bowl" (10) that nationalities, like the ingredients in a mixed green salad, retain their cultural (11) . Earlier generations of (12) believed they had to learn English quickly not only to survive but also for (13) .
Now, many immigrant groups do not (14) the same need. Because there are many places in America (15) you can work, shop, get medical care, marry, divorce and die without knowing English. (16) , Chinatown in San Francisco and New York. Also, Los Angeles has many Vietnamese immigrants and immigrants from Mexico. (17) , many immigrant groups want their children to know their (18) culture. Many Hispanics, for instance, want their children to learn (19) English and Spanish and study the Spanish language in school. They are fighting for the (20) to bilingual education in many communities. In many communities they are in the majority.

肿瘤患者在服用中药汤剂时，应适当忌口和戒吃“发物”，所谓发物是指辛辣燥热刺激、肥甘厚味及低级海产物等一类食物，下列哪种食物不属于“发物”：（）

A、羊肉

B、猪肉

C、螃蟹