A
【解析】
试题分析：考查定语从句和强调句型。本句中when引导的定语从句修饰last month，在第二句中后面省略了强调句型的后半句that he decided to construct the theory of management。句意：—经理什么时候决定修订管理理论的？—是在上个月管理系统出现问题的时候，他才决定重新修订管理理论的。故A正确。
【名师点睛】
强调就是使句子的某一部分比一般情况下显得更加重要。英语表达中，要强调句子的某一成分，一般可用强调句型“It is (was) +that (who) +句子的其余部分”。It在句中无意义，只起引出被强调部分的作用。被强调的部分指人时，除可用that外，还可换用who（强调宾语指人时也可用whom）。使用强调句型时，应注意以下事项：
1、去掉强调结构It is (was) … that(who)…后，剩下的词仍能组成一个完整的句子。这是判断是不是强调句型的关键。试比较：
1. It is strange that he didn’t come yesterday. 2. It is you and Tom that didn’t come yesterday.
显然，句1去掉It is… that …后，句子结构不完整，是主语从句；
句2去掉It is … that …后，句子变为you and Tom didn’t come yesterday. 仍是一个表意完整的句子，这是一个强调句。
再如： 1. It is what you do rather than what you say ____matters. A. that B. what C. which D. this 答案A。这是一个强调主语的强调句型，去掉强调结构，剩下的是What you do rather than what you say matters. 表意完整。
2. That was really a splendid evening. It’s years ____I enjoyed myself so much.
A. when B. that C. before D. since
答案D。由强调句型的判断方法可知，该句不是强调句型。It指时间，句意为：好几年我没有这么高兴了。since的意思是“自从那个时候起”。
2、如果强调时间、地点、原因或方式状语时，不可用when, where, why或how，而仍用that。
试比较：It was because of the accident why he was late. (误), It was because of the accident that he was late. (正)。
又如：
1. It was not until midnight_____ they reached the camp site.
A. that B. when C. while D. as
答案A。该题强干扰项是B，考生容易因强调时间状语until midnight而误选。
2. It was after he got what he had desired ____he realized it was not so important.
A. that B. when C. since D. as
答案A。该句强调时间状语从句after he got what he had desired，题干意思是“得到他所梦寐以求的东西后他才意识到一切都不那么重要”。不要误选B。
3、注意强调句型的否定句和疑问句形式，在这方面很容易因弄不清句子结构而错选。
如:
1. I just wonder ____that makes him so excited.
A. why it does B. what he does C. how it is D. what it is 答案D。正常语序的强调句型容易看出，但要注意它的变体。如果把该题变换一下语序：it is what that makes him so excited,不难看出这是强调句型的特殊疑问句形式，强调了疑问代词what，因为wonder后宾语从句，故用了陈述语序。
2. It was not until she got home ____Jennifer realized she had lost her keys.
A. when B. that C. where D. before
答案B。如果去掉强调结构，该句是一个“not… until”
句型：Jennifer didn’t realize she had lost her keys until she got home. 要强调时间状语until she got home，这时要把主句中的否定词not放在was之后。
4、强调主语时，that或who后面的谓语动词的形式仍然取决于原句中的主语；be的变化只有is和was两种形式，如果要表示现在时将来时的其它各种形式时，就用It is…, 表达过去时的各种形式时，用It was….一般要与谓语动词的时态一致。如： 1. It is I who/ that am an English teacher.
2. It is the boy who/ that speaks English best in the class. 3. It was on Sunday that he gave George this ticket. 4. It is the little girl who/ that has broken the glass.
5、强调句中的时态。如果原句中谓语动词使用的是现在范畴的时态(一般现在时、现在进行时、现在完成/现在完成进行时、一般将来时、将来进行时、将来完成时等)，用It is...that...。如果原句中谓语动词为过去范畴的时态(一般过去时、过去进行时、过去完成时、过去将来时等)，则用It was...that...。
6、在复习中有可能把It is/ was…that句式都误认为是强调句型的几种情况：
1）、把具有实际意义的指示代词it后面接is/was…that误认为是强调句式。
--- Where did you get to know her? --- It was on the farm ____ we worked.
A. that B. there C. which D. where
答案D。该句易误作强调句型，所以A是强干扰项。这里where we worked 是定语从句，修饰the farm。It指“与她相识”这件事。该题很容易受思维定势的影响而拒绝选D，因为平日教学老师一再强调，用强调句型时即使强调地点状语，也不能用where而用that。该句如果要用it was… that强调句型的话，可改写为“It was on the farm where we worked that I got to know her.”
2）、把it指时间、天气、距离、环境等后接be的情形误以为是强调句型。
It was twenty miles from our city to the village ____the accident happened.
A. that B. when C. then D. where
答案D。本题貌似It was…that强调句型，其实不然。句中It表示距离，where 引导地点状语从句。
3）、把It is/ was…that结构的主语从句误认为是强调句型。
1. The Foreign Minister said, “____our hope that the two sides will work towards peace.”
A. This is B. There is C. That is D. It is
答案D。如果选A和C，指示代词This和That在句中找不出指代的内容，选B意义不通。故选D。虽然选It is后题干中出现了It is… that结构，但这不是强调句型。很明显，题干中的that从句应是主语从句，所缺的是形式主语。
7、强调句型It is/ was… that/ who主要用来强调句子的主语、宾语、状语或表语。如果要强调谓语动词,应该用代动词do及其变形does或did，这三种形式常用在谓语动词之前，以加强语气。它一般只能强调现在时与过去时。如：
I do wish I could. 我真希望我能。
He does look well. 他的确看起来气色很好。
You did give me a fright. 你真把我给吓了一跳。
考点：考查定语从句和强调句型
