Answer from cs61c-ae (Zhibo Chen 15283355) for Question 2
C has the following decision statements: if, while, switch case, and for.

MIPS has the following: beq, bne, and slt.

The designers of MIPS probably wanted to include as little unique instructions as possible.  Since all of the other statements in C can be represented by the three MIPS statements, there is no need for anything else.  Also, it is much easier to tell a computer to compare two numbers than to perform an entire loop.