题干
— Mr. Lee _ to a student when I entered the
classroom this morning.
- He is very patient _ _he is young.
classroom this morning.- He is very patient _ _he is young.
A：talking; but
B：talks; though
C：was talking, though
D：talked, however
答案(点此获取答案解析）
C
，则在此过程中发出的光子总数是：