Question about my cars' noise

My car has a noise every time when I just started and went backwards from parking. Sometimes, while running on highway, the noise comes too. But, if I step on the brake, the noise may disappear.

Please, some car experts here tell me what might be wrong with my car and what to do to fix it.

Thanks in advance!

所有跟帖： 

• you need to be more specific...?s like where, how, -iammadaboutu- ♂ (234 bytes) () 09/24/2009 postreply 11:55:42

• 回复：you need to be more specific...?s like where, how, -莫等闲- ♂ (130 bytes) () 09/25/2009 postreply 09:31:13