-Why do you look so sad?
-There are so many problems___
A.remaining to be settled
B.remaining to settle
C.to remain to settle
D.remained to be settled
答：A
译：你为什么看上去很不高兴?
因为有这么多的问题有待解决.
析：There is sth. remaining to be done. ( left to be done)
there be +主语+非谓语动词（现在分词或过去分词）
remain是一个不及物动词,它没有被动语态,sth.和remain之间是主动的关系,所以不用其过去分词,排除D. 而sth. 是将来被解决的,所以后面应用不定式的被动式to be settled,排除BC.
-How long has he____ill?
-About a week. He____ill five days ago
A fallen;was
B been;felt
C been;fell
D fallen;fell
答：C
译：他病了多久了?
约一个星期了.你是五天前病倒的.
析：第一句how long=for how long.? 是现在完成时的延续性用法,用延续性动词be的过去分词,排除fallen排除AD.
第二句话中about a week是He has been ill for about a week 的省略.第三句中five days ago是过去时间.fall的过去式是fell不是felt (它是feel的过去式）,排除B