Mobile phones are becoming more and more popular not only with____(grown-up) but also with students. Meanwhile,they also____(become) a problem for middle schools in the past few years.Some children have got mobile phones____Christmas or birthday gifts,and more will still want them.

    Many like SMS because it is____(ease) and quick.Some parents felt happy because they could communicate with their children.Some teachers said mobile phone use____(be) a distraction（分心的事）to students during school hours and____also gave them much trouble in their classrooms.Sometimes students might use phone messages____(cheat) during exams.A new study found that some teenagers sending messages in class even hurt their fingers because they can't stop____(send) SMS.

    Many teachers suggested that students should not have phones at school,but if there was a good reason,they could leave their phones at school office.And even they can use the telephone in the teachers' office instead.Many people think they understand the reason____parents would want their children to have them,but they agree schools should tell the students____(use) their mobile phones at proper times.

已知热化学方程式：
① C₂H₂(g) +$\frac{5}{2}$O₂(g) == 2CO₂(g)＋H₂O(l) ΔH₁＝-1301.0 kJ•mol^-1
② C(s)+ O₂(g) == CO₂(g)  △H₂＝-393.5 kJ•mol^-1
③ H₂(g)+ $\frac{1}{2}$O₂(g) == H₂O(1)   △H₃ = -285.8 kJ·mol^-1
则反应④ 2C(s)+ H₂(g) == C₂H₂(g)的△H为（   ）

乌鲁木齐的纬度是北纬43°，应记作（    ）