Помогите определить видовеменную форму глагола в английском?Заранее Спасибо.

1) Определить в предложениях видо-вРеменную форму глагола и его залог:
а. Astonomes have measured the exact lenght of the day. - have measured - Present Perfect Active Voice
b. Astronmes find that the day is increasing by 0.002 seconds each century. - find - Present Indefinite (Simple) Active Voice; is increasing - Present Continuous (Progressive) Active Voice
c. The chemical properties of an element are determined by the orbiting electrons. - are determined - Present Simple Passive Voice
d. As a rule one great discovery is generally followed by numerous oters. - is followed - Present Simple Passive Voice

2) Укажите в предложениях Participle 1 и Participle 2 и определите какой частью речи они являются (определение, обстоятельство или часть глагола сказуемого)
a. The cloud chamber is one of the devices used to defect the presence of radioactivity. - used - Participle II - определение
b. Matter consists of one or a number of basic elements occurring in nature. - occurring - Participle I - определение
c. One can use several modern devices while detecting and measuring radioactivity. - detecting - Participle I - обстоятельство
d. When heated to certain temperature, this alloy increases in volume. - heated - Participle II - обстоятельство