- S + V (=be) + C(=whether[if]で始まる節)
a. The problem is whether we should do it now.
b. The question is whether it is possible to feed such knowledge into a computer.
c. What I want to know is whether [if] she was in Nagoya at that time.
- S + V + O + O(=if[whether]で始まる節)
a. He asked me if [whether] I wanted to take a coffee break.
b. Can you tell me if [whether] I can buy two tickets for the concert?
c. We do not usually ask ourselves if this sentence can have any other meanings.