阅读理解。

     A father asks his son, "How many letters are there in the alphabet?" "I don't know," says his son. His

father says, "You don't know? You are in school for many years and you don't know how many letters

there are in the alphabet?" He is very angry. His son says, "No. But let me ask you a question, Dad. You

often go to the post office, please tell me how many letters there are in the post office?"

根据短文内容判断句子正（T）误（F）。

( )1. From this story, we know the son is good at English.

( )2. The son studies at school over (超过) one year.

( )3. The father gets angry because his son is not polite (有礼貌) to him.

( )4. The father knows how many letters there are in the post office.

( )5. There are twenty-six letters in the alphabet.

干燥器采用夹套加热和真空抽吸并行的方式来干燥物料。夹套内通入的是经列管式加热器加热后的热水，而加热器采用的是饱和蒸汽。为了提高干燥速度，应有较高的干燥温度，但过高会使物料的物性发生变化，这是不允许的。因此要求对于干燥温度进行严格控制。如果蒸汽压力波动是主要干扰，应采用（）控制方案。

A.干燥温度与冷水流量的串级控制系统

B.干燥温度与热水温度的串级控制系统

C.干燥温度与蒸气流量的串级控制系统

D.热水温度与蒸气流量的串级控制系统