Which of the following statements is correct

A． The definition phase results in the Software Requirements Specification.

B． Testing is optional in software life cycle.

C． CASE tools can only aid in the design phase of a software life cycle.

D． A change during a later phase does not require the documentation of all earlier phases to be updated.

以下对于宫外孕的描述正确的是（）

A.输卵管峡部异位妊娠发生率最高

B.输卵管壶腹部的破裂症状一般比输卵管峡部严重

C.最常见于卵巢宫外孕

D.宫外孕时，子宫内膜也发生蜕膜变化

E.子宫直肠陷凹穿刺未能抽出血液，则肯定可除外宫外孕