题目内容

When we were young, we ___________ to stay out after 11 o′ clock.

A. hadnt allowed
B. didnt allow
C. werent allowed
D. wouldnt allow

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下列所述为利用生物变异的原理快速培养某种抗除草剂水稻品种的过程．请分析回答问题：（1）从对该种除草剂敏感的二倍体水稻植株上取花药离体培养，诱导成___幼苗。（2）用γ射线照射上述幼苗，目的是_；然后用该除草剂喷洒其幼叶，结果大部分叶片变黄，仅有个别幼叶的小片组织保持绿色．表明这部分组织具有___特性。（3）取上述保持绿色的幼叶小片组织，经组织培养诱导再生植物后，用秋水仙素处理幼苗，

If Penny does the washing, her sister ___________ the table.

A. has cleared
B. cleared
C. is clearing
D. will clear

Children arc very curious ___________.

A. at heart
B. on purpose
C. in person
D. by nature

请阐述遗传学的三大定律并以此解释生物的多样性和变异性。