目前WLAN支持的最安全的数据报文保护机制是（）.

有氧氧化的过程不包括（）。

A.葡萄糖或糖原分解成丙酮酸

B.缺氧时丙酮酸经乳酸脱氢酶催化还原成乳酸

C.有氧时丙酮酸氧化脱羧生成乙酰辅酶A

D.乙酰辅酶A进入三羧酸循环

E.乳酸的生成

某物质和水反应只生成NaOH和O₂，则该物质中（　　）

A．只含有氧元素

B．一定含有钠元素和氧元素

C．只含有钠元素

D．一定含有钠元素，可能含有氧元素

The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.

Providing adequate public health-care facilities is a crucial task in a county like Travis, where more than 60 percent of household incomes are below the poverty line.（）

A. where more than 60 percent of household incomes are

B. where more than 60 percent of household income is

C. which has more than 60 percent of the household incomes

D. where they have more than 60 percent of household income

E. where more than 60 percent of them have household incomes

一般钻头的锋角为（）。

A、45度

B、60度

C、75度

D、90度

开工时加热炉点火前炉子内要处理至测爆合格，燃料气中氧气含量小于（）%时才能拆盲板点炉子长明灯。

A、0.5

B、1.0

C、2.0

D、5.0