A:what the matter wa
B:what was the matter
C:what wrong i
D:what is wrong
Goldfish don't know _______ to them three seconds ago.
种子萌发需要的条件是适宜的____、一定的____和充足的空气,在种子萌发的过程中,首先突破种皮的是____.
我国地理学家胡焕庸提出了一条著名的人口地理界线是( )