1.while my former teacher had been patient with all the students,my new teacher quickly punished those who gave a incorrect answers.
這個(gè)句子里的had been 怎么講?如果是過去完成時(shí),后面怎么沒動(dòng)詞?
2.I worked hard to meet the minimum standards set by the course and to complete assignments on time.
這里的set是什么意思
3.it is critical that students feel comfortable expressing themselves in writing.
expressing前面是不是省略了一個(gè)介詞in