4. We would be grateful if you would introduce us to any companies _____this line of products. (A)engage in (B)specializing in (C)dealt in (D)interesting in 。

6. Much as we would like to do business with you, _____. (A)we are unableto accept your order at the price you requested (B)we will be pleased tofulfill your order No. A116 (C)we are prepared to give a further reductionof 5% in our quoted price (D)we expect to receive a new supply shortly 。