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【简答题】
什么是自花传粉和异花传粉？异花传粉比自花传粉在后代的发育过程中更有优越性，原因是什么？植物如何在的形态结构或开花方式方面避免自花传粉的发生？自花传粉能在自然界被保留下来的原因又是什么？
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皮皮学刷刷变学霸
举一反三
【多选题】Your personal job skills should not be the only factor considered while career decisions. Many other important factors that should be considered include_______
A.
interests
B.
work environment
C.
earning potential
D.
promoion
【单选题】The variances that should be investigated by management include:
A.
only unfavorable variances
B.
only favorable variances
C.
all variances, both favorable and unfavorable
D.
both favorable and unfavorable variances considered significant in amount for the company
【简答题】某显色剂 R 与金属离子 M 和 N 分别形成有色络合物 MR 和 NR ,在某一波长测得 MR 和 NR 的总吸光度 A 为 0.630 。已知在此波长下 MR 的透射比为 30% ,则 NR 的吸光度为 _________ 。
【简答题】某显色剂R分别与一定浓度的金属离子M和N形成有色络合物MR与NR，在一定波长下测得其吸光度分别为0.250和0.150，若某溶液中同时存在相同浓度的这两种有色络合物MR与NR，则其吸光度应为 。
【简答题】人皮肤pH一般在4.5～5.6之间，则皮肤表面显 ______性，如果某人皮肤的pH为8.2，现有下列四种pH不同的洗面奶供选购：①4.5；②6.5；③8.2；④8.5；他最好购买 ______（填序号）号洗面奶．
【多选题】All types of self-completion questionnaires should be accompanied by a cover letter, which should include:
A.
The purpose and significance of the research
B.
The way through which the prospective respondents are selected
C.
The instructions on how to answer and return the questionnaire
D.
A promise of anonymity and confidentiality
E.
An expression of appreciation for the respondents’ time and help
F.
Incentives for returning the questionnaire if there are any
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