A: [blank_start]Why[blank_end] do you work at weekends?
B: Because I can earn more money.
A: [blank_start]Whose[blank_end] pen is this?
B: I think it's John's pen.
A: [blank_start]How[blank_end] did you get here?
B: I took a taxi.
A: [blank_start]Which[blank_end] of these designs do you prefer?
B: I prefer the design on the left.
A: [blank_start]What[blank_end] are you writing?
B: I'm writing an important email.
A: [blank_start]When[blank_end] did you get here?
B: I arrived 20 minutes ago.