大脑确实分为左和右两个部分。

It's true that the brain has a right and a left side.

将头顶板左和右空调组件活门开关打到开位，然后再打到关位。

Turn the left and right air conditioning pack valve switches on the forward overhead panel to ON, then turn the switches to OFF.

视觉系统则要复杂很多。每一只眼睛都具有左和右两个视觉区。

The visual system is even more complex. Each eye has a left and right visual field.

比较两个左和右轮胎，如果一方比另一方，你有凹凸不平的踏穿哪件很可能是造成较大。

Compare both the left and right tyres, and if one side is higher than the other, you have uneven tread wear which is most probably caused by misalignment.