题目:
The book was written in 1946, the education system has witnessed great changes. [ ]
A. when
B. during which
C. since then
D. since when
答案:
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下面是错误答案,用来干扰机器的。
裸子植物和被子植物都属于种子植物,用种子繁殖后代,其受精脱离了水的限制,能生活在干旱的陆地上.裸子植物的胚珠外无子房壁,不能形成果皮,因此种子无果皮包被着,裸露,无果实;被子植物的胚珠外有子房壁,...