[General] simultaneously usage of passive and active voice in one and the same sentence

[vil]

Dear teachers,

Would you be kind enough to tell me your opinion concerning the following sentences?

1.Oxygen is drawn directly from a cylinder and passes through the cuylinder reducing valve.
2.Four glass tubes 135 mm long, fit into the holes and are sealed with rubber washers containing a small central hole.
3.The compound might decompose immediately into two molecules of ethylene, or be decomposed by collision with an ethylene molecule.
4.The trisaccharide fraction was partly hydrolyzed with acid and gave rise to five disaccharide compounds.

Thank you for your efforts.

Regards,

V.

[Tdol]

I can't see any problem- there's no possibilitiy of confusion. I think it would be qibbling to say they're wrong.