关于冠延长术不正确的是（）

A.翻瓣术结合骨切除术

B.切除部分牙龈和牙槽骨

C.只切除牙龈不切除牙槽骨

D.牙根过短不能做冠延长术

E.牙折达到龈下，影响修复者需做冠延长术

Most people have no idea of the hard work. One of the questions that is always asked of me is (1) I became an animal collector in the first (2) .The answer is that I have always been interested in animals and zoos. According to my parents, the first word I was able to say with any (3) was not the conventional "mamma" or "daddy", (4) the word "zoo", which I would (5) over and over again with a shrill (6) until someone, in order to (7) me up, would take me to the zoo. When I (8) a little older, we lived in Greece and I had a great (9) of pets, ranging from owls to seahorses, and I spent all my spare time (10) the countryside in search of fresh specimens to (11) to my collection of pets.(12) on I went for a year to the City Zoo, as a student (13) , to get experience of the large animals, such as lions, bears, bison and ostriches, (14) were not easy to keep at home. When I left, I (15) had enough money of my own to be able to (16) my first trip and I have been going (17) ever since then. Though a collector’s job is not an easy one and is full of (18) , it is certainly a job which will appeal (19) all those who love animals and(20) .

第（11）空应选择（）

A．increase

B．include

C．add

D．enrich