SPF鸡质量检测的样品为()。
A.SPF活体鸡
B.SPF鸡血清
C.SPF鸡蛋
D.SPF鸡血清和蛋
参考答案:D
Jackson returned to Seattle for a while, ______ to Canada, and worked a few jobs there before heading for New York .
A.moving
B.moved
C.being moved
D.having moved
单锚泊时,系留力包括锚的抓力和链的抓力,其中链的抓力与卧底链长和单位长度链重有关:().
A.卧底链长越长,链的抓力越大;锚链越重,链的抓力越大
B.卧底链长越长,链的抓力越小;锚链越重,链的抓力越大
C.卧底链长越长,链的抓力越大;锚链越重,链的抓力越小
D.卧底链长越长,链的抓力越小;锚链越重,链的抓力越小