As there is less and less coal and oil, scientists are exploring new ways of making use of ____ energy, such as sunlight, wind and water for power and fuel.
| A．original | B．alternative | C．convenient | D．staple |
Some people believe ______ has happened before or is happening now will repeat itself in the future.
| A．whatever |
| B．whenever |
| C．wherever |
| D．however |
I found the lecture hard to follow because it ______ when I arrived.
started
B. was starting
C. would start
D. had started
--- What time is it?
--- I have no idea. But just a minute, I ______ it for you.
| A．check |
| B．checked |
| C．will check |
| D．would check |
The best moment for the football star was ______ he scored the winning goal.
| A．where |
| B．when |
| C．how |
| D．why |
______ the forest park is far away, a lot of tourists visit it every year.
| A．As |
| B．When |
| C．Even though |
| D．In case |