哪组互相平行？____哪组互相垂直？____

语法填空

    Writing text messages while walking is dangerous. A study says it is more dangerous than texting while driving. Researchers found that there are more ____ (injury) to texting pedestrians(行人) than there are to texting motorists. Their report says walking is not as easy ____ we think. We must focus on many things at the same time to walk safely in a straight line. The researchers said that people forget how to walk ____ (proper), so dangerous things happen to them. They bump(撞) into walls and other people. They walk into cars, fall over things in the street, ____ even fall into holes.

    A professor said walking is a difficult action. There are several reasons ____ texting makes walking dangerous. ____ is that people cannot see the street. Another is that they focus on their phone keyboard instead of their feet. A final reason is that their minds are somewhere else—they are not thinking about ____ (walk) from A to B safely. The professor said over 6,000 people ____ (visit) his hospital last year because of texting. He said ____ worst cases are head injuries. When a pedestrian is tossed into the air he/she has nothing ____ (protect) the head. The damage can be serious.