Упр. 1. Подчеркните предложения в продолженных временах. 1) We observe now these salts are dissolving in water. 2) Water has appreciable amounts of dissolved salts. 3) He was making an experiment from 2 till 3. 4) He calculated the amounts of substance contained in water. 5) We made many important observations last year. 6) The analyst is determining the properties of the ore now.

Первое предложение, третье и шестое.