单项选择题 1厂组织职工参加周末公益劳动，有80%的职工报名参加。其中报名参加周六活动的人数与报名参加周日活动的人数比为2：1，两天的活动都报名参加的人数为只报名参加周日活动的人数的50%。问未报名参加活动的人数是只报名参加周六活动的人数的（）

单项选择题 射吸式普通割嘴的割嘴头部与割炬连接座的配合角锥度为（ ）度。

未知题型 2. Take a closer look at the following sentences, and correct any mistakes involved. (1) Modern irrigation techniques are more efficiency than traditional ones. (2) Poor diet can lead to a number of healthy problems. (3) After 3 weeks the average high of the plants increased by 12.6 centimetres. (4) Sells of ice-cream usually increase significantly in the summer. (5) The danger of driving too fastly in urban areas was highlighted in the report.