that maths problem is 空格difficult 空格nobody can do it .a:very that_英语解答

that maths problem is 空格difficult 空格nobody can do it .a:very that ; b:so that ; why?

人气：124 ℃　时间：2020-05-10 07:00:30

解答

B
固定词组‘ SO +形容词或副词+THAT 从句’