Conclusions:
I. All Machines being Tools is a possibility.
II. No screw is a Forks.
III. A few Scissors may be Machines. Statements:

From Statement I. Only a few Tools are Machines → All Machines may be Tools (A). Hence conclusion I follows. Only Scissors is Forks → All Forks are Scissors and Forks can have negative relation with anyone. Hence conclusion II follows. Only a few Tools are Machines (I) + All Tools are screws (A) → Some Tools are Screws (I) + Only a few Screws are Scissors (I) → Probable conclusion → Some Scissors may be Machines (I). Hence conclusion III follows.   From Statement II. Only Tools are Machines → All Machines are Tools (A). Hence neither conclusion I nor III follow. Only a few screws are scissors (I) + All scissors are forks (A) → Some screws are forks(I). Hence conclusion II does not follow. From Statement III. Some Machines are Tools (I) → Conversion → Some Tools are Machines (I). Hence conclusion I does not follow. Only a few Screws are Scissors (I) + Some Scissors are Forks (I) → No conclusion (I). Hence conclusion II does not follow. Some Machines are Tools (I) + All Tools are Screws (A) → Some Machines are Screws (I) + Only a few Screws are Scissors (I) → Probable conclusion → Some Scissors may be Machines (I). Hence conclusion III follows.   From Statement IV. Only a few Machines are Tools → Some Machines are Tools (A). Hence conclusion I does not follows. Only Scissors are Forks → All Forks are Scissors and Forks can have negative relation with anyone. Hence conclusion II follows. Some Tools are Screws (I) + Mostly Screws are Scissors (A) → Some Tools are Scissors (I). Only a few Machines are Tools + Some Tools are scissors (I) → Probable conclusion → Some scissors may be Machines (I). Hence conclusion III follows.