单选题The work ______ by the time you decide to cooperate with us.

单选题The______British theoretical physicist Stephen Hawking once said in an interview that heaven is a fairy story for people afraid of the dark.

单选题The entire family is ______ in scientific research.

单选题Some of his suggestions had been rejected ______ they were not practicable. A. as B. when C. until D. if

单选题A. attempt B. charged C. crucial D. delicate E. essentially F. eventually G. expended H. fraction I. individual J. maintain K. minority L. negligible M. scrapping N. slashing O. upsurging Space X launched a cheaper, partially-used rocket into orbit. That's a stride toward 42 the price tag of sending payload to space. Successfully flying reusable rockets is a 43 step toward the dream of sending people to Mars. Until now, rockets have almost all been single-use. Once the fuel is 44 , a rocket stage plummets to Earth, resulting in the destruction of extremely expensive equipment that costs tens of millions of dollars to build. Its founder has likened that to 45 a 747 jet after one flight, which would make air travel impossibly expensive. He has suggested that rocket launches could 46 be much cheaper since the cost of the rocket propellants are less than 1 percent of the full-price ticket for a launch. So, if a rocket could be simply refueled like a jetliner for another flight, the cost of space travel could drop to a 47 of what it is now. The stresses of spaceflight on reused boosters, however, are much greater than those on jetliners. The economics will depend on how many times a booster can be flown, and how much the 48 expense will be to repair the booster each time. Reusable spaceships are not a new idea. NASA's space shuttles were the first real 49 at a reusable spaceship, but the shuttles proved more 50 than hoped, requiring an army of technicians to 51 them between flights. As a result, they ended up being more expensive than expendable rockets.

单选题Scientists are ______certain that there is a cancer-inhibiting agent in the blood of the shark. A.dubiously B.virtually C.queerly D.randomly

单选题The doctors ______the newly approved drug into the patient when he was critically ill. A. injected B. rejected C. projected D. subjected

单选题I hope their plan will work, but they themselves are very______ that it will.

单选题根据下面资料，回答问题。Some farmers in California are having a hard time picking their crops.There are not enough workers to help them with the harvest. One farmer used to grow peaches （桃子）， but will soon grow a

单选题An extensive foundation in the basic sciences should be required of all science students, ______.

单选题Anyone breaking the roles will be asked to leave ______.A. at the spotB. on the spotC. for the spotD. in the spot

单选题Harry Potter fans will instantly recognize the snowy owl as Harry’s famous companion.Hedwig，but these beautiful and powerful owls are easily recognizable not for their magical associations，but for the

单选题选出下面读音不同的选项。

单选题in its 14 years of ______ the European Union has earned the scorn of its citizens and skepticism from the United States.

单选题 Most teenagers in the United States try to make time for school , family and friends． But some choose bigger goals． Here are the stories of two American teens working to make a difference in the w

单选题 Sadly, while the academic industry thrives, the practice of translation continues to ______.

单选题 Your plan, ______, seems impractical.