Every day the mother seems to be busy until 10 o’clock at night, the rest of the family have fallen asleep.
A. that
B. by which time
C. on time
D. whose time
网友回答
A. that
B. by which time
C. on time
D. whose time
解析：根据从句的时态判断,所填词语必须含有“到……时候为止”的意思,并作从句的时间状语。that不可引导非限制性定语从句。on time意为“及时”,不符题意。D项错误,此题无所属关系。