Children，when ______ by their parents, are allowed to enter the stadium.

Today there are more airplanes________ more people than ever before in the skies.

For those with family members far away, the personal computer and the phone are important in staying________.

  the past year as an exchange student in Hong Kong, Linda appears more mature than those of her age.

The film star wears sunglasses. Therefore, he can go shopping without ______..

There are still many problems ______ before we are ready for a long stay on the Moon.

Last night, there were millions of people _______ the opening ceremony live on TV.

__  carefully if any change occurs when doing experiments in the lab..

While waiting for the opportunity to get    , Henry did his best to perform his duty.

— I hope to take the computer course.
— Good idea. ____ more about it, visit this website.