put on sth.简单

So keep it simple: “Hi”, “Hey” or “Hello” — do the best you can to gather all of the enthusiasm and energy you can, put on a big smile and say “Hi”.

所以要简单：“嗨”“嘿”或“你好”——尽你所能聚集起全部的热情和活力，露出灿烂的笑容，说一声“嗨”。

In it, a mother is asked to interact with her child in a normal way before putting on a blank expression and not giving them any visual social feedback: the child becomes increasingly distressed as she tries to capture her mother’s attention.

实验中，母亲先被要求以正常方式与孩子互动，然后摆出一副面无表情的样子，不给孩子任何视觉上的社交反馈：孩子在试图吸引母亲注意的过程中变得越来越苦恼。