dấu hiệu tín hiệu ra hiệu báo hiệu 
signal like: báo hiệu → →
flag semaphore ☊ 
phương pháp báo hiệu bằng cờ ☊ She signalled and pulled over into the slow lane. ☊ lane ☊
The police car signalled to us to pull in. ☊ pull in (to sth) ☊
The siren was a signal for everyone to leave the building. ☊ signal ☊
Don't fire until I signal. ☊ signal ☊
signal (to sb) (for sth): He signalled to the waiter for the bill. ☊ signal ☊
signal to/for sb to do sth: He signalled to us to join him. ☊ signal ☊
The patrolman signalled for her to stop. ☊ signal ☊
signal sb to do sth: She signalled him to follow. ☊ signal ☊
signal sth: The referee signalled a foul. ☊ signal ☊
signal (that)...: She signalled (that) it was time to leave. ☊ signal ☊
signal which, what, etc...: You must signal which way you are going to turn. ☊ signal ☊
Leaving him out of the team may sound the death knell for our chances of winning (= signal the end of our chances). ☊ sound ☊