riddle; puzzle; enigma; enigmatic; mysterious
composition; piece of music; tune; melody; enjoyment; fun
before very long; soon; someday; of the previously mentioned; of that number; among them
still; even now; to this day
to be solved; to be resolved; to loosen; to come untied; to be removed (of restrictions); to be lifted (e.g. a ban)
use; adoption; acceptance; appointment; employment; engagement
chance; opportunity; machine; aircraft; counter for aircraft; counter for (remaining) lives
iron wall; impregnable fortress; impregnable; invulnerable; unassailable
invincible; unrivaled; unrivalled; matchless; unbeatable; undefeatable
all countries; the whole world; universal; all nations
mail service; postal service; mail; mail; postal matter; postal items
fair; exhibition; exposition
exhibiting; showing; putting on display; putting up for sale; entering (a work into a competition); submitting
one machine; one aircraft; one life
after that; afterwards; thereafter
market (financial, stock, domestic, etc.); marketplace; exchange; (street) market
strange; weird; wonder; mystery; cleverness; adroitness
10^12; 1,000,000,000,000; trillion; sign; omen; indication
to be called ...; to be referred to as ...
appearing in unexpected places and at unexpected moments; elusive; phantom
is something that; is that which
possible; potential; practicable; feasible
you have only to; all you have to (do); all that's required; as long as; if only
when it comes to ...; if one were to speak of ...; by ... you mean ...; when you say ... you mean that ...; whenever ...; if it's ... then (without fail)
supposing; even if; granting that; temporarily; provisionally; for the time being
writing; composition; essay; sentence
to obtain; to come into possession of; to get hold of; to get one's hands on
to place persons opposite; to come face to face with; to compare (with); to check (against); to match
funny; amusing; strange; odd; improper; unsuitable
knowing; (an) acquaintance
(former) Imperial Japanese Navy
machine; mechanism; instrument; appliance; apparatus
equation; formula; ceremony; style; (arch.) enforcement regulations (of the ritsuryo)
our country; our land; one's own country
Lewes (Britain); Ruisu; Louise; Luis; Luiz; Ruiz