Small sailboats can easily turn over in the water ________.

if not managed carefully

if are not managed carefully

unless not managed carefully

unless are not managed carefully

What some people regard as a         is seen as a plus by many others.

duty

drawback

failure

faith

考查名词词义辨析。句意：一些人认为是一个缺点，而其他许多人则认为这是一个优点。A.duty责任；B.drawback缺点； C. failure 失败；D. faith信念。根据空后plus“优点”可知，空处需用drawback“缺点”与之对应。故选B项。

Only then_______ how much damage had been caused.

she realized

she had realized

had she realized

did she realize

“only＋状语”位于句首，整个句子用不完全倒装．此外，由then可确定用过去时态．

Dr.Rowan,           secretary resigned two weeks ago, has had to do all his own typing.

whose

of whom 

of which

which

考查定语从句。句意：罗文博士的秘书两周前辞职了，他只能自己打字。          secretary resigned two weeks ago是非限制性定语从句，修饰Dr.Rowan, 引导词在从句中作定语，表示“Dr.Rowan's”，表示“......的”，应用关系代词whose引导该从句。故选A项。

— Father, you promised!

—Well,____．But it was you who didn't keep your word first．

so was I 

so did I 

so I was 

so I did

考查部分倒装“So + be/情态动词/助动词 + 主语”与表强调的“So + 主语 + be/情态动词/助动词”区别。根据语境“you promised（你许诺过）”和答语“But it was …”可知爸爸回答“我的确许诺过”，且promised是过去时，所以表强调要用助动词did,故选D。句意：——爸爸，你许诺过。——好啦，我的确许诺过。但是是你先没有遵守诺言。

We cannot           the punctual arrival of trains in foggy weather.

get

help

guarantee

guess

考察动词词义辨析。句意：我们不能保证火车在雾天准时到达。A. get得到，获得；B. help 帮助；C. guarantee保证；D. guess猜测。根据句意可知，火车无法保证按时到达。故选C项。

it was at 10 pm yesterday______he came home from work.

that

when

which

what

考查强调句。句意：昨天晚上10点他下班回家。考查it+be+强调部分+that+句子，选A。

It was along the Mississippi River _________ Mark Twain spent much of his childhood.

how

which

that

where

此处构成It was...that...强调句式，句中强调了介词短语along the Mississippi River。故选C。