Terms for subject Idiomatic containing string on

English	Russian
on the string	в подвешенном состоянии (In a state of anxious uncertainty • They were supposed to call me last week! How long are they going to keep me on the string like this? thefreedictionary.com Se6astian)
push on a string	впустую тратить силы (буквально: "толкать трос" и т.п. A.Rezvov)