signal的意思
n. 信号，暗号；预兆，征象；动机；导火线
vt. 向…发信号；用动作（手势）示意；以信号告知；
vi. 发信号；
adj. 显著的，优越的；暗号的，作信号用的；
signal的用法
用作名词(n.)
Signals are made with flags or lamps.
用旗或灯传递信号。
We live too far from the city to get a strong television signal.
我们住的地方离城里太远,不能收到清晰的电视图像。
用作不及物动词
S+～(+A)
She is signaling.
她正在发送信号。
The submarine signaled for help.
潜水艇发出求救的信号。
用作及物动词
S+～+n./pron.
She signaled the advance.
她发出信号前进。
A bell signals the end of a school period.
铃声标志着学校里一节课的结束。
S+～+that-clause
She signaled that he was about to turn left.
她打信号灯表示他就要转到左面去了。
S+～+wh-clause
They signaled which way one is going to turn?他们打信号示意走哪一条路。
用作双宾动词
S+～+pron./n.+ton./pron
He signaled a message to his brother.
他用信号向他哥哥发信息。
S+～+(to)n./pron.+to-v
He signaled the waiter to bring the menu.
他做手势要侍者拿菜单来。
The conductor signaled the orchestra to rise.
指挥打手势让乐队起立。
Jim signaled his helplessness to Mary to leave the party.
吉姆无法从宴会脱身时,他向玛丽使了个眼色,表示无可奈何。
S+～+(to)n./pron.+wh-to-v
Tom signaled his friend which way to go.
汤姆示意他的朋友走哪条路。
