リンダは１６歳だが、難なく２０歳で通った。

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

one; best; first; foremost; beginning; start; bottom string (on a shamisen, etc.)

six

-years-old; ability; gift; talent; aptitude; genius

be; is; indicates past or completed action; indicates light imperative

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

easily

two

circle (sometimes used for zero); 'correct' (when marking); symbol used as a placeholder (either because a number of other words could be used in that position, or because of censorship); period; full stop; maru mark; semivoiced sound; p-sound

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

to go by; to go past; to go along; to travel along; to pass through; to use (a road); to take (a route); to go via; to go by way of; to run (between); to operate (between); to connect; to go indoors; to go into a room; to be admitted; to be shown in; to be ushered in; to come in; to penetrate; to pierce; to skewer; to go through; to come through; to permeate; to soak into; to spread throughout; to carry (e.g. of a voice); to reach far; to be passed on (e.g. of a customer's order to the kitchen); to be relayed; to be conveyed; to pass (a test, a bill in the House, etc.); to be approved; to be accepted; to go by (a name); to be known as; to be accepted as; to have a reputation for; to be coherent; to be logical; to be reasonable; to be comprehensible; to be understandable; to make sense; to get across (e.g. of one's point); to be understood; to be straight (e.g. wood grain); to be well-informed; to be wise; to do ... completely; to do ... thoroughly