Don’t worry about the new words. You can _________in a dictionary.

Have you worked in this company for a long time? —- Yes, since I _________ from the college

下列各句中加横线的词，解释有误的一项是（ ）

Mr Read went out of the office, ________ his book on the desk.

The number of students in our class ____ 50. And a number of students _____ planting trees now.