This article reports on a cross-disciplinary inquiry on the effects of instructional medium and disciplinary background on teacher questions and student responses in 20 subject classes at a Chinese university. Data covered 20 lessons delivered by various Chinese teachers in their EMI subjects, where both English and Chinese were employed as instructional mediums. Outcomes state that questioning and answering in the EMI classrooms were unlikely to attain the dual aim of easing students' subject learning and bettering their English proficiency imagined by policymakers.