问题
单项选择题
Container-grown plants can be planted at any time of the year, but ________in winter.
A．should be
B．would be
C．preferred
D．preferably
答案
参考答案：D
解析：词义辨析。should be／would be应是；preferred首选的(adj.)；preferably更适宜，最好是(adv.)；因此应填D。