混凝土配合比试验单上所有项目必须填写清楚明了，不得遗漏、空项，如有不试的项目写“无”或画一道斜杠线。( )
参考答案：对
某化学兴趣小组用铝片与稀硫酸反应制取氢气，以下能够加快该反应速率的是 ①用98%的浓硫酸代替稀硫酸 ②加热 ③改用铝粉 ④增大稀硫酸的体积 ⑤加水 ⑥加入少量硫酸铜 [ ]
A．全部
B．②③⑥
C．①②③⑥
D．②③④⑥
— There was a lot of fun at yesterday's party. You ________ come. Why didn't you?
— What a pity! But I had no time because I had lots of homework to do.[ ]
A. must have
B. should
C. need have
D. ought to have
