From 1892 until his death in 1914, Muir worked assiduously on his writing in an effor

A.until

B.as

C.when

D.before

A.didn’t hear

B.hasn’t been hearing

C.hasn’t heard

D.hadn’t heardv

A.since

B.until

C.when

A.didn’t hear

B.hasn't been hearing

C.hadn’t heard

D.hasn’t heard

A．the author did not understand the importance of giving until he was in late thirties

B．the author was like most people who were mostly receivers rather than givers

C．the author received the same education as most people during his childhood

D．the author liked most people as they looked upon life as a process of getting

According to the passage, it is true that ________.

[A] in the late 19th century in the United States the dividing line between adolescence and adulthood no longer existed

[B] no one can marry without the permission of his parents until the age of twenty-one

[C] one is considered to have reached adulthood when he has a driver’s license

[D] one is not free from the restrictions of child labor laws until he can join the arm

B、In case of anticipatory breach, nonbreaching party's obligations under the contract are not discharged

C、The nonbreaching party must wait until performance is due to sue the breaching party

D、Anticipatory breach can be derived from the conduct of the breaching party without being expressly stated by that party

his memories of the family farm led him into horticulture(园艺).the study habits he had acquired in the orphanage helped him a great deal because he did not care for the life outside his university， and gearhart saw many of his former classmates fall behind， then， as he puts it， he “fell in love with genetics.”

after earning his b. sc. in biological(生物的)science at penn in 1964，he moved to the university of new hampshire(新罕布什尔州)，where he got his m. sc in genetics in 1966. he received his ph.d. degree in genetics， development&embryology(胚胎学)from cornell university in 1970.

through all these years gearhart had only occasional contact with his mother . his studies had led him far from the farming concerns of his family in pennsylvania，when his mother became seriously ill，she came to johns hopkins hospital for treatment， and it was only then， in her last months of life， that gearhart felt he finally came to know the mother who had been forced to give him up so many years before.

on november 10， 1998， john gearhart reported his important findings in genetics. he is now one of the most famous scientists in the united states， a leader in the field of genetics research..

51、John Gearhart was sent to the orphanage because______.

A.his mother was ill

B.his father died

C.his father couldn't support his family

D.his mother didn't like him

52、it can be learned from the passage that ____contributed a lot to his success.

A.one of his brothers

B.his classmates in the orphanage

C.his memories of the family farm

D.his study habits developed in the orphanage

53、John Gearhart attended all the following universities EXCEPT____.

A.Cornell University

B.Pennsylvania State University

C.University of New Hampshire

D.Johns Hopkins University

54、John Gearhart is well-known for his important findings in______.

A.biology

B.horticulture

C.genetics

D.farming

55、John Gearhart didn't understand why his mother gave him up so many years before until ___

A.his mother’s death

B.his great success in his work

C.his mother's last months of life

D.his graduation from Cornell university