名词性从句问题professor lee's book will show you ( )can be used in

名词性从句问题
professor lee's book will show you ( )can be used in other context
A how what you have observed
B how what have you observed
C that you have observed
D whether observed you have
选哪个 为什么 为什么what和how连用 从句怎么好像有两个谓语
some advertisers make us believe( )they advertise will benefit us in many ways
A what B that Cwhich D where
为什么选A 我以为选that 从句缺少啥成分