You'd better open the window and let the fresh air _______a.in b .out c.out of d.into.

You'd better open the window and let the fresh air _______a.in b .out c.out of d.into.
You'd better open the window and let the fresh air _______
a.in b .out c.out of d.into.

You'd better open the window and let the fresh air _______a.in b .out c.out of d.into.
你最好打开窗户让新鲜空气______.
选a.in
let...in 是让...进来的意思
你最好打开窗户让新鲜空气进来.
b.out,意思反了.
c.和d不考虑,因为都是介词,不能不带宾语单独用在句尾.

a
let sth/sb in
把某人某物放进来

a. in

a

a.in
You'd better do sth 你最好做某事
let let sth/sb do sth 让某人或某物做某事
【let sth/sb in 让某人或某物进来】