Here, lets see if this works

I can not tell a great deal from your photos, but I think that you may be under attack from something eating on your plants. The tomato plant looks kinda like a Hornworm may have eaten a bit of the foliage off of it. Someone else may have a better idea about it.
Bill P.

New growth death can mean anything from sunburn to excess nitrogen fertilizer to curly top virus. Given your location my best guess would be excessive sun exposure. Is it possible to shade the plants during the hottest part of the day?

I would try pruning off the damaged growth, let new growth develop and see if it doesn't recover. If it does the same thing then it is likely that you have infected plants.

Over on the Tomato Pests & Diseases Forum there is a post called Tomato Problem Solver. Find it and check out all the links it includes to tomato disease pictures. They will help you narrow down the possible problem and cause.

Good luck. ;)

Dave

Thanks Bill P and Dave.The plants is clearly not eaten by any pest.Well,I'm actually from an Island and there is alot of sun but I have shade on top of the garden.I plant tomato for many times and they grow good and never encounter this kind of problem except this time Since I change seed company.But the seed I bought was from a good company(Yates)