When they get old, some old people go to live in a nursing home with other old people _______ there are nurses to look after them.

Sending Sandra a letter was ________，because her husband might intercept (截取) it

Everyone knows that _____ sun is in the center of thesolar system（太阳系）

Help others whenever you can _______ you will earn respect from others without difficulty

Look! Isn’t that Peter’s sister?—No, it ________ be her—I’m sure she doesn’t wear glasses.