Which sentence is correct?

[Unregistered]

Though he works hard yet he is weak. OR Though he works hard he is weak.

Although he is poor yet he is honest. OR Although he is poor he is honest.

The train has arrived at the platform. OR The train has arrived on the platform.

 

[kfredson]

Though he works hard yet he is weak. OR Though he works hard he is weak.:up:
Or...He works hard, yet he is weak.

Although he is poor yet he is honest. OR Although he is poor he is honest.:up:
Or...He is poor, yet he is honest.

The train has arrived at the platform.:up: OR The train has arrived on the platform.

Use either though or yet, but not both.