胆怯: timidity, timid, cowardly...
质朴: simple, plain, unadorned, unaffected, unsophisticated, rustic, earthy...
定时: to fix a time, fixed time, timed (of explosive etc)...
疙瘩: swelling or lump on skin, pimple, knot, preoccupation, problem...
要不: otherwise, or else, how about...， either... (or...)...
怪不得: no wonder!, so that's why!...
幸好: fortunately...
吓人: to scare, scary, frightening...
到底: finally, in the end, when all is said and done, after all, to the end, to the last...
追溯: to go upstream, to trace sth back to, to date from...
