Our parents won't allow us _____ in the river alone．（ ）
A．swimB．to swimC．swimmingD．swam
You and I are lucky as we've ________ had to worry about finding clean water.
| A． |
often |
B． |
usually |
C． |
never |
________ English has a history of over 2，500 years，the first English dictionary didn't appear until the 17th century.
| A． |
Because |
B． |
Although |
C． |
Unless |
The minute the alarm clock ________，I got up and took a quick shower.
| A． |
went by |
B． |
went out |
C． |
went off |
Remember to use sunglasses to stop the sun from ________ directly in your eyes.
| A． |
shine |
B． |
shining |
C． |
to shine |
Everyone knows now that plastic pollution is ________ huge problem for the environment.
| A． |
a |
B． |
an |
C． |
/ |