NeitherEnglishnorChinese________difficulttolearn.
C
neither …nor…是固定搭配， 意思是：既不……也不……。 它需要遵循就近原则， 谓语动词应与 Chinese 一致，所以答案是 C。
Scientistsdoubtwhetherit’s________toregulateone’sbiologicalclockbydrinking.
Chinaisamountainouscountry.Hills,mountains,andplateauscover_______ofthetotalarea.
________ in thought, he almost ran into the car in front of him.
______isrecognizedasthenationalflag-carrier.
Heshookhandswiththevisitors________astoconveyhisapology.