Everyone knows that________ is dangerous to play with fire, but________ is difficult is to prevent children from playing with fire.
| A．it; it | B．what; what | C．what; it | D．it; what |
Tom ________ in the library every night over the last three months.
| A．works | B．worked |
| C．has been working | D．had been working |
Reading is ________ good habit. Stick to it, and you’ll make ________great progress.
| A．a; / | B．a; a |
| C．the; a | D．/ ; a |
-----May I ask a question after class, Sir?
-----_______, but not during my lunch break.
| A．I’m sorry | B．Anytime |
| C．Certainly | D．Go ahead |
We went through a period _______ communications were very difficult in the rural area.
| A．which | B．whose | C．that | D．when |
A person ______e _mile account is full won’t be able to send or receive any e _mails.
| A．who | B．whom | C．whose | D．whomever |