1.listen, who is playing the violin? it (may be) Lily she loves music. Can the words in brackets be replaced by can be

Can't. can be means speculation. It is usually used in questions. Must be is a definite guess.

Here it is said that it may be Lily. The evidence is not sufficient, so it can only be may be

Stand means to stand, stand up means to stand up

what surprised us is the subject clause, was is the predicate of the main clause

Now, everything is going well on the farm

They want students to get close to the land and learn to help each other outside the classroom.

By selling rice and teaching agricultural courses to residents in the community