a certain doubt among the people as to the practical value of the project.
A. It has
B. They have
C. It remains
D. There remains
网友回答
A. It has
B. They have
C. It remains
(答案→)D. There remains
解析：句意：关于那个工程的实用价值，人们还是心存某种疑虑。there remains...意为“仍有……”，为there be句型的变体。名词doubt往往与there be句型及其变体连用构成固定句型。