题目内容
Exactly______ the potato was introduced into Europe is uncertain, but it was probably around 1565.
| A．whether | B．why | C．when | D．how |
C
解析试题分析：考查主语从句的连接词。句意：准确的说，土豆是什么时候被传到欧洲的还不确定，但是可能在1565年左右。此处when引导主语从句并在从句中作主语。
考点：考查主语从句的连接词。
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| A．that | B．because |
| C．why | D．for which |
_______ that we can't get the necessary equipment, we will have to give up the
experiment.
| A．To assume | B．Assume | C．Assumed | D．Assuming |
Give me a chance, ________ I’ll give you a wonderful surprise.
| A．if | B．or | C．and | D．while |
It is difficult for us to imagine_____ life was like for slaves in the ancient world.
| A．where | B．what | C．which | D．why |
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| A．that | B．why |
| C．how | D．whether |
________ the delayed flight will take off depends much on the weather.
| A．Why | B．When | C．That | D．What |
____ regular exercise is very important, it’s never a good idea to exercise too close to bedtime.
| A．It | B．As | C．Although | D．Unless |
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| A．that | B．how |
| C．when | D．what |