得力

able / capable / competent / efficient

to obtain / to get / to gain / to catch (a disease) / proper / suitable / proud / contented / to allow / to permit / ready / finished

structural particle: used after a verb (or adjective as main verb), linking it to following phrase indicating effect, degree, possibility etc

to have to / must / ought to / to need to

power / force / strength / ability / strenuously