吃水不忘打井人,最早能在低洼的地方开挖水井的原始居民是
读句子,选择适当的词组完成句子。
plant trees by hand cut down one by one have to
a little fall asleep fish and chips a few praise...for
如图是甲、乙两种单基因遗传病的家系图(不考虑基因突变).下列分析合理的是( )