Sammy had fallen asleep by 10.00 o'clock last night这句话的介词by能否用before 时态是过去完成时的话 before可以吗?

Sammy had fallen asleep by 10.00 o'clock last night这句话的介词by能否用before 时态是过去完成时的话 before可以吗?
Sammy had fallen asleep by 10.00 o'clock last night
这句话的介词by能否用before 时态是过去完成时的话 before可以吗?

Sammy had fallen asleep by 10.00 o'clock last night这句话的介词by能否用before 时态是过去完成时的话 before可以吗?
by是说到10点截止才睡觉
before是说10点之前才睡觉
如果用before的话
Sammy had been asleep by 10.00 o'clock last night
fallen换成been 因为fallen是不可持续的动词,用been替换