16.A 依据 This is your captain speaking.
17.C Smoking is permitted only at the back of the passenger cabin (客舱). But you have to wait until the signs at the front of the cabin turned off
18.D We have a duty-free (免税) counter on board. Some cigarettes will be on sale.
19.A Now would you please make sure that your seat belts are fastened (扎紧) for take-off?
20.D 同上一句 没说在哪?