If you meet trouble, you can ______ your friends ________ help.
It is very _______ of you to speak in front of all those people .
---Do you often play computer games? ---No, And so do ________ of my classmates, you know we are very busy
I don’t know _____ or not he will come . _______ he comes , I will call you .
The robot needs _______ once a month. And we will check it for you for free.
We didn’t know how to find them because they didn’t tell us _______.