1. According to Shaw (2010), he found that students in Hong Kong spend over ten hours per week playing computer games.
OR
According to Shaw (2010), he found that students in Hong Kong spend over ten hours per week playing computer games. 
Here, the writer has used a double subject with Shaw and he included; only one is necessary.

CORRECT

As Liu (2009) has shown that teenagers in Hong Kong are becoming addicted to violent role-playing games.

Liu + Vb + that introduce the dependent clause ‘teenagers in Hong Kong are becoming addicted…’  The connective as is not necessary as there is only one clause.

OR

As Liu (2009) has shown, that teenagers in Hong Kong are becoming addicted to violent role-playing games.

Because of the connective as at the beginning the that clause cannot be used.

OR

As Liu (2009) has shown that teenagers in Hong Kong are becoming addicted to violent role-playing games, it is clear that action should be taken to deal with his growing problem.

Both as and the that clause are included but because of this there must be a follow up adjoining clause. In this case as acts like so in this example:

Liu (2009) has shown that teenagers in Hong Kong are becoming addicted to violent role-playing games so it is clear that action should be taken to deal with his growing problem.

CORRECT

In Wong’s (2010) view, she maintains that playing computer games leads to sight deterioration.

OR

In Wong’s (2010) view, she maintains that playing computer games leads to sight deterioration.

Here the writer has used a double subject with Wong and she; only one is necessary.