The manager could have attended the meeting himself.为啥不可以用by

The manager could have attended the meeting himself.为啥不可以用by ___ the meeting ,he would have attended. ____,George would certainly have attended the meeting. He must have attended the meeting yesterday,___he? James attended the meeting and ------- the manager came into the meeting room,() by his secretary About ______students attended the meeting last week. the meeting is well attended是什么意思 --what about the meeting you attended yesterday? She was ill,She can t have attended the meeting here mr smith would certainly have attended the meeting on time b I'm surprised that he should have attended the meeting but h