单选题 She was so ______ in her job that she didn't hear anybody knocking at the door.

单选题 --What do you think of his ______ play? --I like it much-better than his ______ one.

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单选题 Mary, along with her parents, ______ to Paris.

单选题Eat as many vegetables as possible,for they are rich__iron.

单选题Scientists who study the brain have found out a great deal about how we learn.They have_____21_____that babies learn much more from the sights and sounds around them than we_____22_____before.You can?

单选题 Sorry, I mistake your office ______ John's.

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单选题 The boy wanted to ride his bicycle in the street, but his mother told him ______.

单选题 The idea of a fish being able to generate electricity strong enough to light lamp bulbs--or even to run a small electric motor--is almost unbelievable, but several kinds of fish are able to do this. Even more strangely, this curious power has been acquired in different ways by fish be- longing to very different families. Perhaps the best known are the electric rays, or torpedoes (电鱼), of which several kinds live in warm seas. They posses on each side of the head, behind the eyes, a large organ consisting of a number of hexagonal shaped cells rather like a honeycomb. The cells are filled with a jelly-like substance, and contain a series of flat electric plates. One side, the negative side, of each plate, is supplied with very fine nerves, connected with a main nerve coming from a special part of the brain. Current passes from the upper, positive side of the organ downwards to the negative, lower side. Generally it is necessary to touch the fish in two places, completing the circuit, in order to receive a shock. The strength of this shock depends on the size of the fish, but newly born ones only about 5 centimeters across can be made to light the bulb of a pocket flashlight for a few moments, while a fully grown torpedo gives a shock capable of knocking a man down, and, if suitable wires arc connected, will operate a small electric motor for several minutes. Another famous example is the electric eel. This fish gives an even more powerful shock. The system is different from that of the torpedo in that the electric plates run longitudinally(纵向) and are supplied with nerves from the spinal(脊骨) cord. Consequently, the current passes along the fish from head to tail. The electric or gans of these fish are really altered muscles and like all muscles are apt(likely) to tire, so they are not able to produce electricity for very long. The power of producing electricity may serve these fish both for defence and attack.

单选题 John, let's take a taxi, ______?

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单选题 Frankly speaking, I' d rather you ______ anything about it for the time being.

单选题 At dusk they reached ______ small village ______ east of ______ Tai Mountain.

单选题 I thought that the three months there ______ us a lot of good.

单选题 ______ they would support us was a problem.

单选题 Only with your help, ______ such difficulties in the field.

单选题 Tom writes as ______ as her brother.

单选题 Such problems ______ air pollution and traffic jams are becoming more and more serious in some big cities.

单选题 She regretted paying ______ for the camera.