(there's) no telling 成语
I'm telling you|tell
informal It is important to listen to what I am saying.
Marian is a smart girl but I'm telling you, she doesn't always do what she promises.
you're telling me|me|tell|telling|you
interj.,
informal 
Used to show that a thing is so clear that it need not be said, or just to show strong agreement.
"You're late." "You're telling me!" Compare: YOU BET, YOU SAID IT.
no telling
no telling see
there's no telling.
there's no telling
there's no telling It's impossible to determine, as in
There's no telling how many children will come down with measles, or
There's no telling what will happen in the next episode of that soap opera. This idiom uses
telling in the sense of “reckoning,” a usage dating from the late 1300s.
you're telling me
you're telling me I'm well aware of that, as in
She's a terrific dancer.—You're telling me! I taught her how, or
You're telling me, the prices are sky-high here. [Early 1900s]
(there's) no telling
There is no way one can be sure; no one knows or can tell. He's already actual airy at the moment—no cogent how he'll acknowledge to bad account like this. Unfortunately, there's no cogent if such an accomplishment will absolutely construe to a meaningful, abiding advance in the economy.Learn more: no, tellingthere’s no ˈknowing/ˈsaying/ˈtelling...
it is absurd to know/say/tell: There is no cogent what he may do back he gets angry. ♢ There’s no adage what will happen.Learn more: knowing, no, saying
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