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．it, what | D．what, it |
Perhaps it is true that nobody in the world knows exactly how the earth __________.
| A．came up | B．came out | C．came to power | D．came into being |
-- Why don’t we choose that road to save time ?
--- The bridge to it __________.
| A．has repaired | B．is repaired |
| C．is being repaired | D．will be repaired |
The harm which __________ his health is out of our imagination.
| A．was done | B．was done to | C．did | D．did to |
.--- I thought you were going to call on me last night.
--- Sorry, I __________. But I had to finish the report.
| A．would go | B．would have | C．would rather | D．would better |
Don’t be so upset. It won’t be ___________ your children can return
to school again.
| A．long before | B．long ago | C．before long | D．long |