问题
选择题
The problem requires ______.
A．studying with great care
B．to study carefully
C．to be studied without carelessness
D．taking great care of studying it
答案
答案：A
本题考查动词用法。句中require doing =" require" to be done，表示要求做某事。根据句意选择A。句意：问题要求仔细地研究。