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

1.他用力拧了一下那男孩耳朵。

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

2.这束光使人工晶光物，并改变形状，这意味着眼科学家能够调节这些晶状来改变它功效。