Answer Happy

The output of the following gate circuit (U3) is always high, no matter what state Switches A and B are in. UT Output 117 R R Which of these possibilities could account for the output of U3 always being HIGH: The output of U1 is stuck HIGH. R2 is shorted out. The output of Us is stuck HIGH. R3 is shorted out.
In the circuit from below, the last input of GATE 3 is open (floating). 2 OPEN If A=1, B=0, C=1 and D=1, the output Z is equal to: Z=0 Z=1 Z can't be determined