Surgical removal of the thymus from a neonate (新生儿) would result in drastically depleted numbers of which of the following cell types?
A. B cells
B. Mast cells
C. T cells
D. Plasma cells
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Hassall corpuscles are characteristicof which of the following?
A. Blood
B. Keratinizing cells
C. Spleen
D. Red bone marrow
E. Thymus
直角角焊缝的有效厚度he为1.2 hf。
A. 对
B. 错
产生纵向焊接残余应力的主要原因之一是冷却速度太快。
A. 对
B. 错
当钢材为Q235B与Q345B用手工焊接时,宜采用碳钢E50型焊条。
A. 对
B. 错