关于凝血酶时间（TT）的叙述，下列哪项是错误的（）

A.正常人TT为16～18s

B.在被检血浆中加入标准凝血酶溶液，测定其凝固时间即TT

C.又称凝血酶凝固时间（TCT）

D.主要反映凝血过程第一阶段有无异常

E.患者较正常对照至少延长3s以上有诊断意义

假如你叫小华，下面是你收到的你祖父从美国的来信。请你根据来信的内容写一封回信。（要求：100词左右。）

September 15,2005

Dear Xiaohua,

I had a letter from your mother a few days ago ,but she didn’t give me much news about you . She said you went on an ecology summer camp. When I heard that you had seen a snake ,I was worried .I hope someone killed it ! I was sorry to hear that you had hurt your knee. How did that happen? I hope it is better now.

I know your birthday is coming soon ,so I am enclosing（附上）a check for you .Write soon and tell me what you decide to do with the money .I want you to spend it on something nice.

With lots of love,

Yours，

Grandpa

Dear Grandpa,

Yours,

Xiaohua