.The teacher , with 6 gilrs and 8 boys of her class ,________visiting a museum when the earthquake struck.
Although he knew little about the large amount of work done in the field, he succeeded ________ other more well - informed experimenters failed.
—Is the experiment easy? — ________ . I’ll just do my bit.
Apples are usually sold by ________ weight and eggs are sometimes sold by ________ dozen.
.---Will someone go and get Mr. Black? ---He’s already been ___.
__ with such great difficulty, Jack felt at a loss ___.