I. Find out and correct the mistake in each sentence    1.There are not much milk left in the fridge       2.Take the first turning at the left

1. The mistake in the first sentence "There are not much milk left in the fridge" lies in the use of "are" and "much." The correct phrase should use "is" instead of "are" because "milk" is an uncountable noun. Therefore, the corrected sentence is: "There is not much milk left in the fridge."

2. The error in the second sentence "Take the first turning at the left" is in the use of the word "turning." The more appropriate term in this context is "turn." So, the corrected sentence should read: "Take the first turn on the left."

In summary, the problems in the sentences stem from the incorrect use of singular/plural forms and word choice, which are common grammatical issues in English.