1. You should not take on the task because you have to spend a lot of time on it.

2. You should not take the task because you have to spend a lot of time on it.

3.You should not take over the task because you have to spend a lot of time on it.

(Which one is grammatical? Do they ahve any difference among them?)

1 is best; 2 is incorrect; 3 is fine but means something a little different from 1.

1 means that you'd start and finish a task yourself.

3 means that you'd pick up where someone else left off, and then you'd finish the task yourself.

1. "You should not take on the task because you have to spend a lot of time on it." This sentence is grammatically correct.

2. "You should not take the task because you have to spend a lot of time on it." This sentence is also grammatically correct.

3. "You should not take over the task because you have to spend a lot of time on it." This sentence is grammatically correct as well.

All three sentences are grammatically correct, and they have similar meanings. The difference lies in the choice of words used to express the idea.

1. "Take on the task" implies that you are assuming responsibility or accepting the task.
2. "Take the task" suggests that you are accepting or agreeing to do the task.
3. "Take over the task" implies that you are assuming control or responsibility for a task that was previously being done by someone else.

So, the choice between these sentences depends on the specific context and the intended meaning you want to convey.