在光学显微镜下，可以看到细胞内有绿色颗粒。它们是 ，与植物的 作用有关。
叶绿体；光合
my English teacher, I have become what I am.[ ]
A. Thanks for
B. Thank to
C. Thanks to
D. Thank for
. –You see, I’m poor in maths, you are not good at English, and……
--That’s_________we should help each other.
A．when
B．where
C．how
D．what
