The scientist __________ the experiment for half a year, but he _______ yet.
A．made; didn’t succeedB．made; hasn’t succeeded
C．was making; didn’t succeedD．has been making; hasn’t succeeded
D
考查時(shí)態(tài)。根據(jù)for half a year可知應(yīng)該使用完成時(shí)，再根據(jù)句意可知完成進(jìn)行時(shí)符合句子的意思。Yet也和完成時(shí)連用。結(jié)合句意可知D正確。句意：半年來那位科學(xué)家一直在做那個(gè)實(shí)驗(yàn)，但他還沒有成功。
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