[填空题]You are wasting time (persuade) __________ him to join us. He is stubborn(顽固的).

[填空题]You are wasting time (persuade) ______ him to join us. He is stubborn(顽固的).

[填空题]You are wasting time (persuade) __________ him to join us. He is stubborn(顽固的).

[简答题]precious spend realize wasting time wasting money make full use of build...into

[填空题]If you had spoken to him last time you saw him, you（）(know) what to do now.

[单项选择]You’re（）your time trying to persuade him; he’ll never join us.
A. spending
B. wasting
C. losing
D. missing

[单项选择]A. You will not persuade him.
B. You are getting nowhere with him.
C. You cannot sell your ice to him.
D. You should not Waste time cutting ice with him.

[填空题]Even if you should fail to persuade him，______________________________(也不要失望)．

[单项选择]It is virtually impossible to persuade him to apply for the job.
A. simply
B. almost
C. totally
D. completely

[单项选择]You never see him, but they’re with you every time you fly. They record where you are going, how fast you’re traveling and whether everything on your airplane is functioning normally. Their ability to withstand almost any disaster makes them seem like something out of a comic book. They’re known as the black box.
When planes fall from the sky, as a Yemeni airliner did on its way to Comoros Islands in the India ocean June 30, 2009, the black box is the best bet for identifying what went wrong. So when a French submarine(潜水艇) detected the device’s homing signal five days later, the discovery marked a huge step toward determining the cause of a tragedy in which 152 passengers were killed.
In 1958, Australian scientist David Warren developed a flight-memory recorder that would track basic information like altitude and direction. That was the first mode for a black box, which became a requirement on all U.S. commercial flights by 1960. Early models often failed to withstand crashes, however, So in 1965 the device was completely redesigned and moved to the rear of the plane--the area least subject to impact--from its original position in the landing wells(起落架舱). The same year, the Federal Aviation Authority required that the boxes, which were never actually black, be painted orange or yellow to aid visibility.
Modem airplanes have two black boxes: a voice recorder, which tracks pilots’ conversations, and a flight-data recorder, which monitors fuel levels, engine noises and other operating functions that help investigators reconstruct the aircraft’s final moments. Placed in an insulated(隔绝的) case and surrounded by a quarter-inch-thick panels of stainless steel, the boxes can withstand massive force and temperatures up to 2000℉. When submerged, they’re also able to emit signals from depths of 20000ft. Experts believe the boxes from Air France Flight 447, which crashed near Brazil on June 12009, are in water nearly that deep, but statistics say they’re still likely to turn up. In the approximately 20 deep-sea crashes over the past 30 years, only one plane’s black boxes were never recovered.What does the author say about the black box
A. It ensures the normal functioning of an airplane.
B. The idea for its design comes from a comic book:
C. Its ability to ward off disasters is incredible.
D. It is an indispensable device on an airplane.