Rock-climbing is a breathtaking activity, very popular nationwide among young people, ______ cooperation as well as courage plays an important role.
| A．who | B．which | C．where | D．of which |
Is oxygen the only gas ________ helps fire burn?
| A．that | B．/ | C．what | D．it |
The number of the people present at the concert was _____ than expected. There were many tickets left.
| A．much smaller | B．much more |
| C．much larger | D．many more |
The silk road, _______ Marco entered China, was important for the exchange of goods and ideas.
| A．which | B．along which | C．after which | D．where |
—Would you please lend me some gas?
—Sorry, I have ________ it.
| A．use up | B．run out | C．gone out | D．run out of |
The singer hopes her concert will be like a big party ________ everyone enjoys themselves.
| A．which | B．when | C．what | D．where |