Idea

Chen Mo frowned a little with displeasure, but he nodded as he said that he didn't see which way she went.

Although he knew that it wasn't the time to get displeased about something, he didn't feel very happy either.

"I didn't, at that time, I was busy taking care of Mom," Chen Mo clearly remembers how Chen Yu asked him by sign not to tell anyone where she went.

Of course he won't tell Mo Ling anything, lest she falls in danger because of his big mouth.

If she has decided to make a move, then no matter what or how she did, Chen Mo will always support her.

Mo Ling frowned when he failed to take any information out of Chen Mo. 

'This guy  is hard to deal with, he won't tell me anything!'

'I have to find out by myself!'

"Well, then. If you really don't know, then sit here and take care of the rest. I can help you to find your sister and get your brother back. But it looks like you are unwilling to have them back, right?" Mo Ling asked him with a provoking manner.