显微镜下观察到人的一个细胞中染色体已分成两组,每组23条,那么,可以肯定每组染色体中
Put your maths book ______ your desk . A.at B.on C.the
I have __________ English book. A.a B.6 C. an
Turn the light. A./ B.on C.in
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你想知道你班新来男同学的姓名,你问其他同学说: A.Where is my storybook ? B.What`s his name?