在编制、审批施工组织设计或施工方案和冬雨期施工措施时，必须同时编制、审批安全技术措施，如改变原方案时可以不必重新报批。( )

Cumulus clouds that have undergone vertical development and have become cumulonimbus in form，indicate（）.

A.clearing weather

B.that a warm front has passed

C.probable thunderstorm activity

D.an approaching hurricane or typhoon