Out of the crowded bus _______, who was dressed in a black suit and waved to a woman.
| A．a tall man in his thirties stepped | B．stepped a tall man in his thirties |
| C．did a tall man in his thirties step | D．did a tall man step in his thirties |
They _____ be at home. You see, the door is locked from the outside.
| A．may | B．must | C．mustn’t | D．can’t |
______ you return those books to the library immediately, you will have to pay a fine.
| A．Until | B．Unless | C．If | D．Provided |
The teacher began by _____ us where the city was and went on ______ about its history.
| A．telling...to talk | B．to tell...to talk | C．telling...talking | D．to tell...talking |
Human be haviour is mostly a product of learning, ____ the behavior of animals depends mainly on instinct.
| A．whereas | B．so | C．unless | D．that |
_______ from the hill, the whole city of Nanjing looks more beautiful.
| A．As people see | B．Seeing | C．People see the city | D．Seen |