Semiconductor are merely reasonable conductors of electricit

三极管翻译
A thyristor unit is semiconductor device which acts as a switch formed by two thyristors in ant parallel. To switch on the alternating current the input signal will be on and the thyristor will switch off at first Zero Crossing voltage with no input signal.
The benefits of thyristor units compared with electromechanically contactors are numerouses: no moving parts, no maintenance and capacity to switch very fast. Thyristors are the only solution to control transformers and special loads that change resistance with temperature and with age.

semiconductor chips are small in size and light in weight.这句话什么意思?

英语翻译
Nanostructured Semiconductor Films for Photocatalysis.Photoelectrochemical Behavior of SnO2/TiO2 Composite Systems and Its Role in Photocatalytic Degradation of a Textile Azo Dye
作者是：K．Vinodgopal,Idriss Bedjia,and Prashant V.Kamat
时间大概是：1996年左右吧.

英语翻译
1.Tunnel diode——a semiconductor diode,discovered in 1957 by L.Esaki,based on the tunnel effect.It consists of a highly doped p-n semiconductor junction,which short circuits with negative bias(偏压) and has negative resistance over part of its range when forward biased.Its fast speed of operation makes it a useful device in many electronic fields.In a tunnel diode the shape of the characteristic for current and voltage is affected sharply by the tunnel effect,with a large tunnelling current associated with tunneling from the valence band to the conduction band.As the forward bias on the junction is increased the tunnel effect becomes less and less pronounced.
2.Tunnel effect——an effect in which electrons are able to tunnel through a narrow potential barrier that would constitute a forbidden region if the electrons were treated as classical particles.That there is a finite probability of an electron tunnelling from one classically allowed region to another arises as a consequence of quantum mechanics.The effect is made use of in the tunnel diode.
3.That there is a finite probability of an electron tunnelling from one classically allowed region to another arises as a consequence of quantum mechanics.这句话中的主要谓语是哪一个?

英语翻译
The operation of semiconductor chemical sensors is underlain by variation of the electrophysical characteristics of the sensing layer of the semiconductor sample,induced by the change of the composition of the gas medium analyzed.
不要用在线翻译工具翻译完不看就直接复制给我啊-