（）研究事物为什么会发生，回答“为什么”和“怎么样”。
A.描述性研究
B.解释性研究
C.行动研究
D.档案袋研究
参考答案：B
—May I speak to John?
---Sorry, he Japan. But he in two days.
A．has been to; will come back
B．has gone to; will come back
C．has been in; would come back
D．has gone to; come back
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