1.He gave the boy’s ear a painful tweak.

1.他用力拧了一下那男孩的耳朵。

2.This causes it to polymerise and then change shape, which means the ophthalmologist can tweak the lens to alter its power.

2.人工晶体上的物质聚合，并改变，意味着眼科学家能够调节些晶体来改变它的功效。