按照国际标准化组织(ISO)及我国最新标准,铸造合金的分型主要是根据_____和_______这2项力学性能而分,其中_________型合金适用于高刚性和高强度的修复体。
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薄壁压铸件的致密度高,可相对提高压铸件的()和()。压铸件壁厚增加,()和()也随之增加,故在保证压铸件有足够的强度和刚度的前提下应尽量减少压铸件的()并保持各截面厚薄()。
充填速度指的是金属液在()作用下通过()进入型腔时的()。
27____was 25 times more deadly than normal and it caused more deaths than the First World War.
The consequences of a massive 28____could be disastrous for 29____.For example, a cloud of ash could 30_the sun and the molten lava would destroy everything in its path.
26. A. virus B. chemical C. epidemic D. wave
27. A. impact B. disaster C. pandemic D. eruption
28. A. forest fire B. tsunami C. greenhouse gas D. volcanic eruption
29. A. terrorists B. scientists C. humanity D. mass migration
30. A. block out B. head for C. put out D. wipe out