1 to ambush

2 to lie in wait for

3 to lie low

4 ambush

1 to hide

2 to cover up

3 to conceal

1 to move up and down

2 to undulate

3 ups and downs

1 surname Fu

1 to bend over one's desk (writing, studying, taking a nap etc)

1 hidden genius (idiom)

1 lit. so numerous that one could just bend down and pick them up (idiom)

2 fig. extremely common

3 easily available

1 bowed head and ears glued (idiom); docile and obedient

2 at sb's beck and call

1 to bow before (idiom)

2 to capitulate

1 danger lurks on every side (idiom)