Subgroups of $E_8$ by using extended Dynkin diagrams

I need to show that the following are subgroups of $ E_8$ using extended Dynkin diagrams.

$ $ SU\left(5\right)\times SU\left(5\right)$ $ $ $ SU\left(3\right)\times E_6$ $ $ $ SU\left(4\right)\times SO\left(10\right)$ $ and $ $ SO\left(16\right)$ $ $ $ SU\left(2\right)\times E_7$ $ $ $ SU\left(9\right)$ $

Is it enough to find the Dynkin diagrams for the subgroups by deleting edges in the Dynkin diagram for $ E_8$ ? If so, I can only seem to do this for the first ones listed.

Is the use of extended Dynkin diagrams important?