行车中要文明驾驶,礼让行车,做到不开英雄车、冒险车、赌气车和带病车。
参考答案:对
It's time _________ school. Let's _________.[ ]
A. to; go
B. for; go
C. for; to go
植物组织培养的理论依据是什么?其优点如何?