The biggest problem for most plants, which______just get up and run away when threatened, is that animals like to eat them.
人和动物的染色体上本来就存在着与癌有关的原癌基因和抑癌基因.其中原癌基因主要负责____;抑癌基因主要是____ .
Jack has ____ (been/fallen) ill for two weeks.