the lock and key for a gate

to close and lock a gate

toil, hardship / worry, anxiety

toilsome, painstaking / worrisome

to toil, to work hard / to worry

to open / to make (a hole)

to broaden; to become wide / to develop; to progress; to improve / (of a person) to be enlightened; to be inspired; (perfect tense) to be sharp or clever

a chain

a gate / (religion) a sect, school of thought / (biology) a phylum, division / Short for 門限 (mongen): a curfew

frontier pass / close / relation / barrier / gate