Don't worry about him. ________he grows older,he will learn to deal with different problems properly.
A:When
B:While
C:As
D:After
有人说,青春是一颗划破天宇的流星,虽然绚烂却很短暂;也有人说,青春是一棵长青树,永不凋零。你认为决定青春的最重要的因素是( )
秋水仙素诱导多倍体形成的原因是
甲乙两台机器,功率之比为2:3,工作时间之比为1:3,则它们所做的功之比为____ .