I sooner but I didn’t know that they were waiting for me.
| A．had come | B．was coming | C．would come | D．would have come |
Mr. Smith didn’t understand _____ made his son so upset that evening.
| A．what was it | B．why it was this | C．how that was | D．what it was that |
— How can I wake up so early?
— Set the alarm at 5 o’clock, you’ll make it.
| A．but | B．or | C．and | D．so |
Tom _________ in the library every night over the last three months.
| A．works | B．worked | C．has been working | D．had been working |
Although cats can not see in complete darkness, their eyes are much more _______to light than human eyes.
| A．brilliant | B．attractive |
| C．available | D．sensitive |
There’re more than 100 elements found in nature, ______ are metals.
| A．most of which | B．most of them | C．most of that | D．most which |