The plan is under study. 本句be動詞後,普通名詞study前,不需要加冠詞a, or用studying嗎？文法上如何解釋。?

Re:-TW Chen--the heart of grammar:- The plan is under studying (gerund, to spend time in learning,examine carefully, (the noun study is uncountable).-----not a subject.

因為句中解作"調查"(act of examining something in detail)的study是不可數名詞, 所以不能加上冠詞a (indefinite article)!