upper contact的意思|示意

At this point the upper stem has lost contact with the diaphragms. The valve should be opened to this point but not back seated.

在此时，上阀杆已经失去了同横膈膜的接触。阀门应该开启到这一点，但不能反向固定。

In order to avoid the attack of these illnesses, should contact the use of timing conditions to car oil, and moderate oil, usually between upper and lower oil scale as well.

为了避免这些毛病的发作，应当联系运用条件定时给轿车换油，并使油量适中，通常以机油标尺上下限之间为好。

Sound: play open strings alone; play slow scales, sustaining a 20- to 30-second bow; practice everything in the lower or upper half; or watch your contact point in the mirror.

音色︰只用空弦拉奏；慢慢地拉奏音阶，一弓维持在 20-30 秒；所有以上半弓或下半弓练习；或对着镜子看（弓的）接触点。