以下哪个事件图元可以放置到人工活动上（）
A、错误中间件事件图元
B、开始时间图元
C、结束事件图元
D、取消中间件事件图元
参考答案：A
根据中文意思及句意，写山相应的单词。
1．How many colours are there in a _________ (彩虹)?
2．I'm busy these days, I haven't __________ (答复) to Jim's last e-mail.
3．colours Can change our __________ (心情).
4．Mr. Smith is 60 years old. But he is still _________ (精力充沛的).
5．Animals in forests are busy getting ready for the _________ (即将到来的) winter.
安健环体系有哪些关键环节？
