At the beginning of a speech, it is very important to grab the audience's attention and make them interested in ______ you have to say.
A. which
B. what
C. that
D. who
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We must find out ____ Jackson is coming, so we can book a room for him.
A. when
B. how
C. where
D. why
I wonder ________ Mary has kept her figure after all these years.—By working out every day.
A. where
B. how
C. why
D. if
简述渗透压的形成原理,并分析我们平时喝的纯净水是如何得到的。
关于心绞痛,叙述错误的是:
A. 心肌急性暂时性缺血缺氧所致
B. 可产生放射痛
C. 含服硝酸酯类药物可缓解
D. 持续时间长
E. 属CHD的一种