Question

______ I admit that all these problems are difficult, I don’t agree that they can’t be solved.

A．Unless

B．While

C．Until

D．Since

Answer 1

B

词义辨析。Unless除非……否则；While尽管；Until  直到；Since
自从，因为，由于。句意：尽管我承认这些问题都很难，但是我不认为它们不能被解决。所以选B。