Thanks, Clive. By the way, could you tell me why I should remove 'on' of the above sentences? Unfortunately I can't distinguish when I have to use 'on' from when I must not.
By the way, could you tell me why I should remove 'on' of the above sentences? Unfortunately I can't distinguish when I have to use 'on' from when I must not.
It's really rather idiomatic, which makes it hard to teach and hard to learn. Just read as much as you can, and listen to English as much as you can.