I won’t call you, ________ something unexpected happens.
A. unless
B. whether
C. because
D. while
_______ he had not hurt his leg, John would have won the race.
A. If
B. Since
C. Though
D. When
Small sailboats can easily turn over in the water ______ they are not managed carefully.
A. though
B. before
C. until
D. if
The field research will take Joan and Paul about five months; it will be a long time _____ we meet them again.
A. after
B. before
C. since
D. when