GMAT 97.5 S3/15
Madagascar was one of the last habitable areas of the earth to undergo human settlement,which has made it an idea site for researching rare flora and fauna.
a)Madagascar was one of the last habitable areas of the earth to undergo human settlement,which has made it
b)Madagascar was one of the last habitable areas of the earth to have undergone human settlement,and that has made it
c)Madagascar underwent human settlement as one of the last havitable areas of the earth,which makes it
d)Madagascar, one of the last habitable areas of the earth,underwent human settlement,making it
e)Because Madagascar was one of the last habitable areas of the earth to undergo human settlement, it is
key E
my choice A
难道过去时态和现在完成时态不能出现在同一句子中吗？
GMAT 97.5 S7/4
In June,1981,six teenagers in the villag of Medjugorie,Yugoslavia,claimed to have had visions of the Virgin Mary,who they say has continued to appear to them over the ensuing years.
a)claimed to have had visions of the Virgin Mary,who
b)claimed to have visions of the Virgin Mary,whom
c)claimed to have had visions of the Virgin Mary,whom
d)claimed to have visions of the Virgin Mary,who
e)had claimed to have visions of the Virgin Mary,whom
key A
my choice C
A和C的区别就在于非限制性定语从句中，“，”以后先行词表示人用who还是用whom的问题，我怎么记得应该是：先行词在句子中充当主语用who，充当宾语用whom。还是GMAT有特殊规定呢？望指正！
GMAT 97.5 S7/22
Cardiopulmonary resuscitation should begin between one to four minutes after a cardiac arrest in order to be a success.
a)Cardiopulmonary resuscitation should begin between one to four minutes after a cardiac arrest in order to be a success.
b)Between one and four minutes after a cardiac arrest,cardiopulmonary resuscitation should begin to be successful.
c)Successful cardiopulmonary resuscitation should be begun from one to four minutes after a cardiac arrest occurs.
d)It it is to be successful,a cardio arrest should be treated with cardiopulmonary resuscitation one to four minutes afterward.
e)To be successful,cardiopulmonary resuscitation should begin within one to four minutes after a cardiac arrest.
key E
my choice C
我的问题是：
1 from和 within的差别是什么？
2 是不是因为begin一般不用被动语态，所以不选C？fficeffice" />

第一题的关键在于在gmat里面，which和that都不能指代前面的整个句子，只能指代前面的一个名词，而a,b,c中明显是用它们指代了前面整句话。d前后用两个逗号，使中间变成同位语，后面making用动名词修饰，使整个句子没有了谓语，也错，所以e。关键不是在考时态！！！fficeffice" />

第二题不管gmat中讲究不讲究，这里都应该用who嘛，who has continue to.....who是后面的主语嘛，又不是谓语。老兄，这明明都是语法题嘛，说什么是逻辑难题，骗偶来看！！

第三题，对！的确不该用被动，而且读一读，不觉的within 放在这里意思更明确嘛。它要表达的是在一段时间之前，而不是在强调在一段时间之间