欧美日韩黄网欧美日韩日B片|二区无码视频网站|欧美AAAA小视频|久久99爱视频播放|日本久久成人免费视频|性交黄色毛片特黄色性交毛片|91久久伊人日韩插穴|国产三级A片电影网站|亚州无码成人激情视频|国产又黄又粗又猛又爽的

The doctor will not perform the operation ___ it is absolutely necessary.

A. when               B. if                  C. for                  D. unless

The doctor will not perform the operation ___ it is absolutely necessary.

A. when               B. if                  C. for                  D. unless

The doctor will not perform the operation ___ it is absolutely necessary.

A. when               B. if                  C. for                  D. unless

The doctor will not perform the operation ___ it is absolutely necessary.

A. when               B. if                  C. for                  D. unless

The doctor will not perform the operation ___ it is absolutely necessary.

A. when               B. if                  C. for                  D. unless