environmental damage is done, it takes many years for the ecosystem to recover.
| A．Even if |
| B．If only |
| C．While |
| D．Once |
Sor
ry， I didn’t hear you. I to the music.
| A．just listened | B．was just listening | C．has just listened | D．had just listened |
The fact has worried many scientists the earth is becoming warmer and warmer these years.
| A．what | B．which | C．th at |
D．though |
If one succeed， one must put his heart into his career.
| A．will | B．is going to | C．is to | D．is about to |
The book was written in 1946， the education system has witnessed great changes.
| A．when | B．during which | C．since then | D．since when |
My wallet isn’t in my bag. Where I have put it？
| A．can | B．must | C．should | D．shall |