guide RNA, gRNAs (向导RNA)

指导RNA（guide RNA）

Direction: There are 20 blanks in the following passage. For each blank there are four choices marked A, B, C and D. Choose the ONE answer that best fits into the passage. Then mark the corresponding letter on the Answer Sheet with a single line through the centre.
Dogs are often (21) man’s best friend. For those who are blind, a dog is (22) than a friendly company. A dog is a pair of sharp eyes. A (23) dog guide gives blind people the (24) to move through the world safely and freely. A dog guide is also a best friend. (25) a working team of a dog and a person is not easy. There are no factories making thousands of dog guides a day. There are however, schools all (26) the country that train both blind people and the dogs they depend upon. The process of education is long for both the dog its human partner.
A dog begins schooling as puppy. Around age of 8 weeks, the puppy is placed with a faster family. There it (27) training and gets used to (28) around people. When a dog is about a year old, it goes off to school for a series of tests. These tests help the school (29) whether the dog is likely to make a good guide. Dogs that fail the tests are placed in permanent homes. (30) that pass the tests go into a training (31) .
For the next four-to-six months, the dog learns everything (32) needs to become a dog (33) . The dog learns to stay focused. It learns to ignore food, smell, and other animals. It learns to remain (34) by such noises such (35) shouting or music from a passing ear radio. It learns to (36) commands like" right", "left" or" forward". The dog learns to stop before every curb and stairway and to (37) moving objects. In short, good dog guides learn to keep their (38) safe while they go about the everyday actions of life. A dog that (39) completed training will be (40) a master.

A:guide  B:training  C:test  D:blind

It was with the help of the local guide __________ the mountain climber was rescued.

A:who B:that C:when D:how

We agree to accept （　）they thought was the best tourist guide.

A:whatever B:whichever C:whomever D:whoever

With the guide ______ the way, we set out on foot into the night dark.

A:lead B:leading C:led D:to lead

Dogs are often【C1】______man’s best friend. For those who are blind, a dog is【C2】______than a friendly company. A dog is a pair of sharp eyes. A【C3】______dog guide gives blind people the【C4】______to move through the world safely and freely. A dog guide is also a best friend. 【C5】______a working team of a dog and a person is not easy. There are no factories making thousands of dog guides a day. There are however, schools all【C6】______the country that train both blind people and the dogs they depend upon. The process of education is long for both the dog and its human partner. A dog begins schooling as puppy. Around age of 8 weeks, the puppy is placed with a faster family. There it【C7】______training and gets used to【C8】______around people. When a dog is about a year old, it goes off to school for a series of tests. These tests help the school【C9】______whether the dog is likely to make a good guide. Dogs that fail the tests are placed in permanent homes. 【C10】______that pass the tests go into a training【C11】______ For the next four-to-six months, the dog learns everything【C12】______needs to become a dog 【C13】______The dog learns to stay focused. It learns to ignore food, smell and other animals. It learns to remain【C14】______by such noises such【C15】______shouting or music from a passing car radio. It learns to【C16】______commands like "right", " left" or " forward ". The dog learns to stop before every curb and stairway and to【C17】______moving objects. In short, good dog guides learn to keep their【C18】______safe while they go about the everyday actions of life. A dog that【C19】______completed training will be【C20】______a master.【C13】

A:guide B:training C:test D:blind

The guide shoes are secured to the crosshead by means of .

A:through bolts B:end chock bolts C:side chock bolts D:tap-bolts