at, about, on, of, with

【小题1】Dong Lei is talking ________ Miss Smith in the classroom.
【小题2】There are five kilos ________ tomatoes in the box.
【小题3】—Is Mr. Guo at the office?
—No. But you can call him ________ 6957683.
【小题4】A lot of people are getting ________ the train.
【小题5】—How many students in your class will go to the zoo tomorrow?
—________ twenty.