再请教三道

1。in 1981 children in the us spent an average of slightly less than two and a half hours a week doing household chores; by 1997 they had spent nearly six hours a week

  chores; by 1997 that figure had grown to nearly six hours a week

  chores; whereas nearly six hours a week were spent in 1997

  chores, compared with a figure of nearly six hours a week in 1997

  chores, that figure growing to nearly six hours a week in 1997

2。

until recently, the inuit people led a nomadic existence, sheltering in igloos, the ice-block domes that are peculiar to north-central Canada, and in structures made of stones, bones, driftwood, and skins.

  During recent times, the inuit people lead a nomadic existence, sheltering

  In the times that are recent, the inuit people led a nomadic existence, sheltered

Up until recently, the inuit people, leading a nomadic existence, have sheltered

  Until recent times, leading a nomadic existence, the inuit people were sheltered

3。

Trans world entertainment corporation, which owns the record town and Saturday matinee retail chains, announced that since sales of up to one-fourth of its stores are poor, they will be closed

  it is closing up to one-fourth of its stores, which accounted for its poor sales

  it was closing up to one fourth of its stores because of poor sales

  to be closing, on account of poor sales, up to one-fourth of its stores

1。in 1981 children in the us spent an average of slightly less than two and a half hours a week doing household chores; by 1997 they had spent nearly six hours a week

  chores; by 1997 that figure had grown to nearly six hours a week

  chores; whereas nearly six hours a week were spent in 1997(选这个)

  chores, compared with a figure of nearly six hours a week in 1997

  chores, that figure growing to nearly six hours a week in 1997

2。

until recently, the inuit people led a nomadic existence, sheltering in igloos, the ice-block domes that are peculiar to north-central Canada, and in structures made of stones, bones, driftwood, and skins.

选A

  During recent times, the inuit people lead a nomadic existence, sheltering

  In the times that are recent, the inuit people led a nomadic existence, sheltered

  Up until recently, the inuit people, leading a nomadic existence, have sheltered

  Until recent times, leading a nomadic existence, the inuit people were sheltered

3。

Trans world entertainment corporation, which owns the record town and Saturday matinee retail chains, announced that since sales of up to one-fourth of its stores are poor, they will be closed

  it is closing up to one-fourth of its stores, which accounted for its poor sales

  it was closing up to one fourth of its stores because of poor sales

  to be closing, on account of poor sales, up to one-fourth of its stores(选这个)

1。in 1981 children in the us spent an average of slightly less than two and a half hours a week doing household chores; by 1997 they had spent nearly six hours a week

  chores; by 1997 that figure had grown to nearly six hours a week

  chores; whereas nearly six hours a week were spent in 1997

  chores, compared with a figure of nearly six hours a week in 1997（我选这个）

  chores, that figure growing to nearly six hours a week in 1997

   这种题目我最头疼，请教解题思路，望潜龙NN不吝赐教

找不出来为何用完成时，要么答案有误，要么题目有误。这是我的观点。选A的nn能否解释一下，in 1981用过去时，而by 1997 用过去完成时。

从未见过这种用法，请执教！！！！

2。

until recently, the inuit people led a nomadic existence, sheltering in igloos, the ice-block domes that are peculiar to north-central Canada, and in structures made of stones, bones, driftwood, and skins.

  During recent times, the inuit people lead a nomadic existence, sheltering

  In the times that are recent, the inuit people led a nomadic existence, sheltered

Up until recently, the inuit people, leading a nomadic existence, have sheltered

  Until recent times, leading a nomadic existence, the inuit people were sheltered

   为什么选这个而不选A，请赐教

D凌乱而且时态不对，所以，理应是错误的。答案是错误的

3。

Trans world entertainment corporation, which owns the record town and Saturday matinee retail chains, announced that since sales of up to one-fourth of its stores are poor, they will be closed

  it is closing up to one-fourth of its stores, which accounted for its poor sales

  it was closing up to one fourth of its stores because of poor sales

  to be closing, on account of poor sales, up to one-fourth of its stores

   为什么选这个而不选A？？请指点

   潜龙NN是高手，给的和答案都一样，还请指点一二。不胜感激