一Whom would you like to be your assistant，Jack or David？ 一If I had to choose，David would be__________choice.

And they can ______their passports______，making leaving or “escaping” virtually impossible.

—When can I call on you, afternoon or evening?
—________. I’ll be at home all the time.

______means that a program written for one computer system can be compiled and run on another system with little or no modification．

Can we ______ another worker to help Jimmy or find another solution?

In ______, the only element that can be deleted or removed is the one that was inserted most recently.

My camera can be _____ to take pictures in cloudy or sunny conditions. ( )

Scientists say it may be five or six years _____ this medicine is tested on human beings.

It will be a relief over the death of a friend or a relative if the friend or relative dies from ______.

______no air or water, there would be no life in the world.

1990年，美国麻省理工学院斯隆管理学院的彼得·圣吉教授出版了一本享誉世界之作，引起世界管理界的轰动，这就是________。