A:种子的胚已破坏
B:土壤潮湿不够
C:土壤温度太低
D:阳光不够充分
He is a strict teacher, but all the students like him. I don't know why.
非洲有世界最大的____ 沙漠,世界最长的河是____河,世界最大的盆地是 ____ 盆地。