英语的问题：是元音字母前要加an，还是元音音标前加an

音标

Faced with a growing number of transgenic food, people's awareness is not unanimous, the US-led faction of the main eating and the European-led opposition on a global scale formed two camps. Recent survey showed that the United States, Canada, the two most consumers have accepted genetically modified

元音音标前

音标是元音音标前用an

绝对是元音音标前

元音音标前啊！
元音字母比如u不加，音标是ju：
呵呵