下列图示的实验装置或操作正确的是（　　）

1914年的萨拉热窝事件成为第一次世界大战的导火线，其实质是(       )

增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1.每处错误及其修改均仅限一词；2.只允许修改10处，多者（从第11处起）不计分。

    The summer holiday is coming.My classmates and I are talking about how to do during the holiday.We can chose between staying at home and take a trip.If we stay at home,it is comfortable but there is no need to spend money.But in that case,we will learn little about world.If we go on a trip abroad,we can broaden（拓宽）you view and gain knowledges we cannot get from books.Some classmates suggest we can go to places of interest nearby.I thought that it is a good idea.It does not cost many,yet we can still learn a lot.