I don’t want to make friends with those people ______ think of themselves first when in trouble.

____________the window. What’s happening there？

It is _______ difficult for us _______ climb up the mountain.[ ]

After a series of food safety incidents, the government has ______ that not enough has been done to guarantee people green and healthy food.

If you want to get good grades, ____________, you should listen to the teacher _________ in class.