他在社交媒体上总是摆出一副成功人士的样子。

He keeps ___posing as a successful businessman on social media.

孩子们在相机前摆姿势拍照。

The children were ___posing in front of the camera for a picture.

这个问题给学生带来了很大的挑战。

This question is ___posing a big challenge to the students.