根据下图回答问题
图中表示R基的字母是(),表示肽键的字母是()
参考答案:B、C、G;E、F
While we were running on the playground,Jack suddenly stopped ___________ and lay on the ground,so we all stopped ___________ what was wrong with him.
A.running; to see
B.running; seeing
C.to run; to see
D.to run; seeing
自动绞缆机的作用是:()
①、无需人工带缆;
②、减少值班人员操作;
③、保持缆绳受力平衡并防止缆绳被拉断;
④、不受潮汐风力的影响
A.①、②、④
B.②、③、④
C.①、③、④
D.①、②、③