let (someone) onorlet on (someone):to allow (someone) to get on a bus, an airplane, etc.让…上(车、飞机等)
They let passengers with small children on (the airplane) first.他们让带着小孩的乘客先上(飞机)。
The bus stopped to let on a few more passengers.公共汽车停下,让几名乘客上了车。
2
let onorlet on (something)informal:to tell, admit, or show that you know something说出;表明;透露
He knows a lot more than he lets on.他知道的比他透露出来的要多得多。
Don't let on that I told you!别说是我告诉你的。
She was unhappy, but she never let on. = She never let on to anyone that she was unhappy. [=she never showed or told anyone that she was unhappy]她不开心,但她从来没有表现出来。