Is there a need for an arithmetic shift left instruction?

A good answer might be:

No. A logical shift left moves zeros into the low-order bit, which is correct for both signed and unsigned integers.

The sra Instruction

Here is the MIPS instruction that performs an arithmetic shift right: 

sra    d,s,shft   #  $d <-- s shifted right
                  #  shft bit positions.
                  #  0 =< shft < 31

Sometimes you need to divide by two. This instruction is faster and more convenient than the div instruction.

QUESTION 14:

Does the sra instruction give the correct results for unsigned integers?