"道钉撬 " 、 "扳手" 、 "人体前臂的杠杆 "
分别属于 省力杠杆?还是费力杠杆?
道钉撬 " 、 "扳手属于 省力杠杆
"人体前臂的杠杆属于 费力杠杆
"道钉撬 "是省力杠杆
"扳手"是省力杠杆
"人体前臂的杠杆 " 是费力杠杆