Mark the letter A, B, C or D to indicate the correct answer to each of the following questions

43. In order to help human beings live longer and healthier, many scientists are working hard __________ they can invent new drugs.

            A. so that       B. as not to                C. in order that not               D. in other to

44. Many bridges in London are covered with wooden roofs _________ it can be protected from rain and snow.

            A. so that not             B. so as to      C. in order that not               D. in other that

45. Please arrive on time ________ us to be able to start the meeting punctually.

            A. so that not             B. as not to                C. in order for           D. in other that

46. The laser beam can attack directly and accurately the diseased cells ___________ the healthy neighbors are left unharmed.

            A. so that       B. as not to                C. in order that not               D. in other to

47. My father and  I do morning exercises every day ___________ improve our health.

            A. to not       B. as not to    C. in order that not   D. to

48. We learn English ________________ we can communicate with other people.

            A. so that        B. because                C. that                                  D. so that to

49.He studies very hard so that _______________ pass his final exam next month.

            A. not to          B. in order to           C. so as not to                        D. so that to

50. ___________ waste electricity, we turn out the lights when there is enough light.

            A. so                B. so as not to          C. that                                   D. so that to