A warm thought suddenly came to me _______ I might substitute the hero to buy some flowers for his mother’s 60th birthday.

  A. if             B. when             C. that             D. which

The fire spread fast．Luckily the local government had brought it under control___the situation got worse．

    A．though                B．until                    C．before                    D．since

---Do you think the weather will be all right this summer?

---No, _______ we’re lucky. The newspaper says it’ll be very hot anyway.

A. unless                      B. if                           C. though                            D. as

       Mr. Green has two sons, one of _____ working as a bus driver now.

A. who                         B. whom                      C. them                        D. whose

—He is eager to try something he has never tried before.

    —Oh, I see. That’s _______ he’s different from others.

A. when               B. where     C. how       D. what

The process of producing electricity may also give out CO2, _______ you heat your house with electricity instead of charcoal.

   A. even if                       B. as long as               C. as if             D. as soon as

Now my hometown is not at all _______ a traveler who visited it ten years ago can expect.

   A. that              B. what                C. which                D. where

When the environmentally friendly cars came onto the market, many people were eager to buy them ________ the price.

   A. wherever            B. however                  C. whichever           D. whatever

---Did your father come back early last night?

---Yes. It was not yet eight o’clock ______ he arrived home.

A. before      B. when       C. that         D. until

---What are you going to do this afternoon?

---I will probably go for a walk         it stays fine.

A. unless       B. so long as           C. even if             D. as if