请用下列方框中词组的适当形式完成句子。

He tried so hard to stay awake, but ______________he fell asleep.
If we plant trees every spring, in a few years’ time the mountain ____________________trees.
I found your pen _____________ when I was cleaning the room.
In business, success not only__________________ what you say but also how you say it.
I am surprised that a quarrel _______________ between the two neighbours because   they used to be close friends.
The police are still _____________ the lost boy though it is midnight.
The village among the mountains was ___________because of the heavy rain.
---I suppose your student doesn’t understand you.
----____________, he understands me very much.
It’s getting dark;___________, it is beginning to rain.
______________, I’d like to thank you for all you’ve done for me.