As the name suggests, a geochronologist is a scientist who ______ terrestrial materials in order to ______ them.

多项选择题Once though to be ______, the dawn redwood was rediscovered in the 1940 s, at which time its continued survival seemed ______; today, however, it is commonly cultivated.

多项选择题Alexis complained that Jim ______ too quickly when their parents imposed a curfew: instead of negotiating, he complied without protest.