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【单选题】
设对某角观测一测回的观测中误差为±3′′,现要使该角的观测结果精度达到±1.4′′,需观测( )个测回。A.
5
B.
4
C.
3
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【单选题】My cousin is _____________ sometimes. It’s hard for him to change his mind even though his idea is not right.
A.
stubborn
B.
imaginative
C.
energetic
D.
practical
【单选题】Although he sometimes lost his temper, his pupils liked him______for it.
A.
not so much
B.
not so little
C.
no more
D.
no less
【简答题】请观看视频17分51秒处,描述 常见的 箱型截面的类型,并说明各自适应什么情况?
【简答题】wonderful的比较级是( )
【单选题】His radio is a very old one. It sometimes works and sometimes it_______
A.
seldom does
B.
does hardly
C.
never does
D.
doesn’t
【单选题】用pH试纸测定某无色溶液的pH时，规范的操作是
A.
将pH试纸放入溶液中观察其颜色变化，跟标准比色卡比较
B.
将溶液倒在pH试纸上，跟标准比色卡比较
C.
用干燥的洁净玻璃棒蘸取溶液，滴在pH试纸上，跟标准比色卡比较
D.
在试管内放少量溶液，煮沸，把pH试纸放在管口，观察颜色，跟标准比色卡比较
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