函数f（x）=ax+loga（x+1）在[0，1]上的最大值与最小值的和为a，则

What does the speaker mean a. His performance in the exams made him the head 0fhis class: b. His performance in the exams made him feel very exhausted. c. His performance in the exams was often mentioned by him. d. His performance in the exams made him feel complacent.

城市维护建设税按纳税人所在地的不同，设置了三档地区差别比例税率。纳税人所在地为市区的，税率为( )。

A．(A) 1%

B．(B) 3%

C．(C) 5%

D．(D) 7%

人体所需要的维生素种类很多，主要有四种：_________、_________、_________、_________。

下列影响骨折愈合的因素中哪项是引起骨折不愈合的最主要因素（）

A.粉碎性骨折

B.固定不确实

C.开放性骨折

D.年龄大

E.感染