You Do Need power plug adapter while traveling from Gambia to China.

Here is Why You Need An Adapter

The outlet and plug type used in China are A, C and I and in Gambia is G. This is how they look like.

Gambia

In Gambia, outlets of type G are in use.

Type G

China

In China, outlets of type A, C and I are in use.

Type A

Type C

Type I