Silk ______ one of the primary goods traded along the Silk Road by about 100BC.( )
had become
was becoming
has become
is becoming
__________ the program , they have to stay there for another two weeks.
What worried the child most was _______ to visit his mother in the hospital.
Clearly and thoughtfully________, the book inspires confidence in students who wish to seek their own answers.
________ late in the morning,Bob turned off the alarm.
The girl is a student at Oxford University, _____ for a degree in English literature.