English is difficult __________ well in a short time.
.People like taking photos because photos are the _______ of youth and history and can remind us of many happy scenes.
A much better way must be found to achieve an equal ________ of the resources.
Unfortunately, the element Madam Curie devoted all her life her death.
Out of the crowded bus , who was dressed in a black suit and waved to a woman.
When exposed to stress, in ________ form, all of us react both chemically and physically.