This is _______ difficult problemthat few students can work it out.

下列四个选项中对加点实词的解释全都正确的一项是（ ）

下列句子加横线词语不是古今异义词的一项是

We can see light in his office. He___________ be in his office.

9The other day he ran across one of his friends on the street, whom he ___________for ages