There is _____ what the weather will be like.
| A．not knowing | B．no knowing | C．not know | D．no known |
Don’t be afraid of asking for help _______ it is needed.
| A．unless |
| B．since |
| C．although |
| D．when |
Food shortage will long be a worldwide problem _______ much has been done to supply enough for everyone.
| A．before | B．if |
| C．since | D．although |
I do every single bit of housework _______ my husband Bob just does the dishes now and then.
| A．since | B．while | C．when | D．as |
_______ the Atlantic Ocean crosses the equator, the trade winds cause a flow of water to the west.
| A．That | B．When |
| C．Where | D．Though |
To enjoy the scenery,Irene would rather spend long hours on the train _______ travel by air.
| A．as | B．to |
| C．than | D．while |