单选题 The machine must be kept within a temperature range of 50 to 75 degrees Fahrenheit to achieve ______ performance.
  • (A) diverse
  • (B) optimal
  • (C) sequential
  • (D) relative


【正确答案】 B
【答案解析】[词汇] optimal最佳的
[错误答案] (A)相异的(C)连续的(D)相关的