Chọn từ thích hợp:
1. It's time (for / at / on) ................. lunch.
2. They get (on / up / in) .............. at six o'clock.
3. He is ( a / the / an) ....................... engineer.
4. She goes to work ( to - from / from - on / from - to) .................. 7.30 a.m ................... 4.30 p.m.