<p>1，piloted flights to mars have not been planned (because it requires) costly and complicated technology.
the answer is because they would require, instead of as they are requiring which i chose, why?</p>
<p>2,despite receving praise for its special effects, the movie was criticized because its characters were so weak as (being) scarcely believable.
Being is the answer, why</p>
<p>3, for much of the last centruy, the building industry relied heavily on the availablity of the timber, but now that forest resources are being depleted rapidly, builders must decide what to do about (it)
The answer is it, why? </p>
<p>thanks for help</p>
<ol>
<li><p>I think " would require" is correct due to the usage of present perfect. Present perfect refers to an action that occurred at unspecified past and still continues until present time. Back to the question, pilot flight have not been planned ( present perfect, occurred in the past–>until now) + the reason " would require …( prediction of future happening in the past–> makes the usage of “would” is grammatically correct. Therefore, we should use "would+ V1 than present tense “require or are requiring”</p></li>
<li><p>To me, Being should be replaced by " for being " scarcely believable. There are so (adj) as+to+ verb & so ( adj) as+for+noun+gerund. I’m not too sure about this.</p></li>
</ol>
<p>3.I think it is wrong because of vague pronoun usage. “It” can refer to “the availability of the timber” which is not the case here. I think it here refers to the condition the building industry embroiled in.</p>
<p>Hope this help! I might be wrong haha</p>