Good technique in medicine means less pain and fewer deaths and, ________ it is our duty to master it．

1. A.
   altogether
2. B.
   therefore
3. C.
   otherwise
4. D.
   however

Good technique in medicine means less pain and fewer deaths and, _____ it is our duty to master it.

A. altogether　　B. therefore　　C. otherwise　　D. however

Good technique in medicine means less pain and fewer deaths and, _____ it is our duty to master it.

A．Altogether        B．therefore          C．otherwise         D．however

Good technique in medicine means less pain and fewer deaths and, ___, it is our duty to master it.

　A. altogether B. therefore C. otherwise D. however

Good technique in medicine means less pain and fewer deaths and, ________, it is our duty to master it.

[　　]