为预防胎儿神经管畸形，孕妇补充叶酸的有效时机是（）。_不同生理人群营养_全学科试题题库

当前学科：不同生理人群营养

题目：单选
为预防胎儿神经管畸形，孕妇补充叶酸的有效时机是（）。
答案： <查看本题扣1积分>

查看答案

答案不对？请尝试站内搜索

推荐知识点:

Materials and Tools for Language Learning ① The range of materials and tools available to help you with your language studies is huge, from dictionaries to language courses. All of them can help you in different ways, and the appropriate use of these materials and courses will make your language learning much easier and more effective. ② Possibly the most useful tools there are for learning a language are dictionaries. Dictionaries come in a number of formats including bilingual, monolingual, illustrated, electronic and online. Bilingual dictionaries are perhaps the most useful ones for beginners and intermediate learners, while monolingual dictionaries, which are designed for native speakers, are also useful for advanced learners. Pocket dictionaries are good for quick reference and easy to carry around. Larger dictionaries are better if you want more definitions, examples of usage, and information about pronunciation, and grammar. Electronic dictionaries are available as handheld units, or as software. Handheld ones are portable, easy and quick to search, and often provide other functions, such as, text-to-speech, voice recognition and speech synthesis organizers, address books. They tend to be rather expensive though. Software dictionaries offer many of the same functions, and can be used on computers, and mobile phones. ③ The traditional courses tend to consist of textbooks containing dialogues, exercises, notes on grammar, and maybe cultural information. Accompanying cassettes, CDs and/or mp3s are often available. Most such courses are intended for complete beginners or people with only minimal knowledge of the language. Intermediate and advanced-level courses are available for some of the popular languages, such as French, German, Italian and Spanish. ④ Audio courses usually consist solely of cassettes or CDs, though some may also include a limited amount of printed material. All dialogues, exercises, instructions and explanations are recorded and the focus of these courses is teaching you to understand and speak the languages. They are very good at teaching you authentic pronunciation and a manageable amount of vocabulary. ⑤ Various computer-aided courses are available on CD-ROMs and DVDs. Each course is different but they generally include dialogues, audio, exercises and tests. Some also include phrasebooks, dictionaries, videos, games and provide online and/or telephone support. With audio courses, you can learn（）

齿轮泵在齿轮合处相贴合的固定件面上有一对凹槽，其作用是（）。

炭疽的好发部位是()

胃脾韧带下份内含（）。

土壤电阻率的单位是（）。

简述三相异步电动机的工作原理，并列举几种常见故障？

截瘫患者术中休克的原因下列哪项最不可能()

食品生产经营者的生产经营条件发生变化，未依照本条例第二十一条规定处理的，由有关（）责令改正，给予警告；造成严重后果的，依照食品安全法第八十五条的规定给予处罚。

上市公司非公开发行股票未采用自行销售方式或者上市公司配股的，应当采用（　）方式。

用纱线,扁条,绳,索,缆制其他物品