Electronic devices such as iPods and headphones can do great harm to our hearing if _______ improperly.

_______, the experiment will be successful.

—What’s that noise?
—There’s a truck stopping outside. It’s someone _____ something.

_____ time, the teacher had us do half of the exercises in class and complete the other half for our homework.

When _____ about one of the biggest concerns today, many citizens mentioned the sharp rise in housing price.

The girl _______ a green coat looks more elegant than her companion.

____our mother will allow ____ to see a film after supper?

______ a mile in the fastest time while doing gymnastically correct lunges is yet another event______ Ashrita is outstanding.

Early peoples moved around, ______ the herds of animals.

Liu Xiang earned the respect from the whole world as he hopped down the track to the finishing line, ____ the last hurdle.