—May I see your ticket, please? I think you ________ in my seat.
—Oh, you’re right. My seat is upstairs. I’m terribly sorry.
| A．are sitting | B．sit | C．sat | D．have sat |
I had to shout to make myself _______ above the noise.
| A．heard | B．hearing | C．heard | D．to hear |
.He walked down the hills, _______ softly to himself.
| A．sing | B．singing | C．sung | D．to sing |
.At this moment the bell rang _______ the end of class.
| A．announce | B．announcing | C．announced | D．to announce |
The child sat in the dentist’s chair _______.
| A．tremble | B．trembling | C．trembled | D．to trembled |
Properly _______ with numbers, the books can be easily found.
| A．marked | B．mark | C．to mark | D．marking |