Use a singular verb with sums of money or periods of time. Ex) Ten dollars _____ a high price to pay.Ten dollar is a sum of money, so you have to use a singular verb. In this case, the subject acts as a unit.I'll give you another example.ex) Ten years is a long time.In this sentence 'ten years' is a period of time. When a subject is a period of time, you have to use a singular verb though the subject has a plural form.Look at the exception.ex) Ten years have passed since he died.In this case, you should use a plural auxiliary verb, 'have' because ten years indicates the process of time.-------------------------------Hello. Good to see you again.Is my explanation of grammatical points correct? If I didn't explain well, would you correct them?