溶质质量分数为3x％和x％的两种硫酸等体积混合后，混合液中溶质的质量分数是（）

甲房地产开发商与乙建筑施工企业签订了一份施工合同，双方在合同中未约定纠纷的处理方式。后来由于工程质量问题发生了纠纷，双方决定将此纠纷提交该市仲裁委员会仲裁。则下列说法中，正确的是( )。

A．由于双方在合同中未约定处理纠纷的具体方式，所以只能通过和解的方式解决纠纷

B．由于双方在合同中未约定采用仲裁的方式处理纠纷，所以发生纠纷后不能通过仲裁解决

C．由于双方在发生纠纷后约定采用仲裁的方式处理纠纷，所以可以通过仲裁解决纠纷

D．由于双方在发生纠纷后约定采用仲裁的方式处理纠纷，所以不能通过和解解决纠纷

冠心病诊断最可靠的方法是（）

A.心电图检查

B.X线检查

C.冠脉造影

D.超声心动图检查

E.心导管检查

He said that what Mary had bought from the supermarket that morning ________ only a     few potatoes, eggs and salt, but I don’t think what he said ________ true.

A．are;are

B．were;is

C．is;is

D．were;are

凝汽器管内沉积物的沉积量在评价标准（）及以上时，应进行沉积物化学成分分析。

A. 一类

B.二类  

C.三类

Sometimes we have specific problems with our mother; sometimes, life with her can just be hard work. If there are difficulties in your (1) , it’s best to deal with them, (2) remember that any (3) should be done (4) person or by letter. The telephone is not a good (5) because it is too easy (6) either side to (7) the conversation.

Explain to her (8) you find difficult in your relationship and then (9) some new arrangements that you think would establish a (10) balance between you. Sometimes we hold (11) from establishing such boundaries because we are afraid that doing (12) implies we are (13) her. We need to remember that being (14) from our mother does not (15) mean that we no longer love her. If the conflict is (16) and you cannot find a way to (17) it, you might decide to give up your relationship with your mother for a while. Some of my patients had (18) "trial separations". The (19) allowed things to simmer down, enabling (20) .

4（）

A.by

B.for

C.to

D.in