单选题 We want such materials _____ can bear high temperature and pressure.

单选题 The concept of television, _____ images over distances, had intrigued scientists even before the invention of moving pictures or radio.

单选题 Since there are so many cars on the road, _____ many hours to complete a short journey at peak times in some major cites.

单选题 At the beginning of the 20th century, people made coffee _____ a cloth bag full of coffee grounds into boiling water.

单选题 Every product _____ before it is sold.

单选题 _____ to flow spontaneously from a block of ice to a surrounding volume of water, this could occur in complete accord with energy conservation.

单选题 _____ turn up late at the meeting, he _____ forgot his relevant documents.

单选题 Farmers and hunters considered them to be _____ real and dangerous as the wolves and bears that lived in the wilder parts of the countryside.

单选题 _____ started mowing the lawn _____ it started raining.

单选题 _____ hundreds of pieces of litter.