She looked up and formed another smile under the mask.

When the man left the room and closed the door, he was still laughing under his mask.

For the first time he realized that under the mask of their daily relations these two were anything but friends.

I frowned, not that he could see it under the mask.

Under the mask, the older woman's face is covered with sores.

Under his mask, he flushed, relieved that it could not be seen.

The nurse backed away, making little noises under her mask.

He was still tense under the mask of his friendly grin.

When surface mount technology came about, there were problems caused by the tin/lead under the mask.

Under the mask of gentility, she was furious with him.