The beautiful sunset our attention，and we stopped to watch it.
| A．caught | B．paid | C．fixed | D．slipped |
If ____ in, the viruses can result in illness or even deaths.
| A．breathed | B．to breathe | C．breathes | D．is breathed |
Standing inside ____ lots of strange creatures with white skin and large black eyes.
| A．was | B．is | C．were | D．be |
—I have been waiting for you so long.
—Sorry, I have been in the library, _______ my friend look for some books.
| A．helped | B．helping | C．to help | D．help |
I think humour is a vital form of entertainment, ____ it makes us laugh and laughing keeps us healthy.
| A．when | B．after | C．if | D．because |
The UN is an important international organization _____helps many people around the world.
| A．who | B．that | C．where | D．/ |