Thank you, sir for your reply. May you explain to me the structure of the second second? I'm sorry to say that I'm not convinced that the second sentence is correct .
A million dollars is a lot of money to risk in the stock market. The recent robberies are causing major concerns in the community. 500 miles is too great a distance to drive.
The singular is used only when the multiple units can easily be considered a single quantity. That is not true of the robberies or the children-- and especially when the plural (as with 'concerns'